Methods And Systems For Respiratory Monitoring With Photoplethysmography

ABSTRACT

The present invention relates to optimized gas supply utilizing photoplethysmography. Flow rate, pressure or amount of gas is adjusted as a function of blood oxygen saturation data, photoplethysmography signals, or both, obtained from the pulse oximeter probe.

CLAIM OF PRIORITY

This application is a continuation of Ser. No. 11/535,295, which is acontinuation of U.S. patent application Ser. No. 10/751,308, Filed Jan.2, 2004, which is a continuation in part of application Ser. No.10/749,471 filed Dec. 30, 2003, now U.S. Pat. No. 7,024,235, which is acontinuation in part of application Ser. No. 10/176,310, filed Jun. 20,2002, now U.S. Pat. No. 6,909,912 and International Application No.PCT/US03/19294, filed Jun. 19, 2003, and claims benefits under 35 U.S.C.§120 for all above-noted applications. These patent applications arehereby incorporated by reference into this application in theirentireties.

FIELD OF THE INVENTION

The present invention relates to the field of non-invasive measurementof signals indicating arterial blood oxygen saturation by means of pulseoximetry, and of photoplethysmographic signals indicating pressure andflow characteristics, and in particular, configurations of a pulseoximeter probe that sample across the cheek or the lip of a livingsubject. Such probes optionally include provision of a supply of oxygenor oxygen-enriched gas to a patient whose blood oxygen saturation isbeing measured, and/or a sampler of exhaled breath for capnography.

BACKGROUND OF THE INVENTION

Diseases, acute injuries, and other conditions can adversely affectblood flow to and in the limbs. In a general sense, agents and factorsthat may affect and lower circulation to the limbs, also known asperipheral circulation, include certain drugs, especiallyvasoconstrictors, poor perfusion per se due to shock, such as resultsfrom low blood volume, or septic or cardiogenic shock, certain traumas,external pressure (as from burns), hypothermia, and other mechanicalabnormalities or injuries. In particular, decreased peripheralcirculation may be caused by a number of disorders within the bodyincluding, but not limited to, atherosclerosis, Raynaud's disease,Buerger's disease, chronic obstructive pulmonary diseases (COPD), andembolic occlusive disease.

Poor blood flow reduces the amount of oxygen that is carried in theblood stream to cells. Emergency rooms, intensive care units, burnunits, operating rooms, and ambulances treat a variety of critically illpatients in need of continuous monitoring of real time hemoglobinsaturation and/or blood pressure readings. If oxygen levels in the bloodbecome very low at peripheral sites, a variety of problems may occurwhich include inadequate resuscitation, cell death or necrosis that canlead to non-healing lesions, gangrene and amputation of limbs. Also, inprogressive diabetes and other conditions that may result inatherosclerosis that affect peripheral circulation and perfusion,non-invasive measurement of circulation and/or resistance status isuseful to monitor the progression of the disease and the effectivenessof treatments.

Also, many patients, especially among the elderly, are on chronic oxygentherapy; they are in need of supplemental oxygen on a routine basis.Such patients may have impaired and/or diminished cardiopulmonarycapacity. When such patients are ambulatory, their supply of oxygen(usually a tank of compressed oxygen or liquid oxygen) must betransported with them wherever they travel. Oxygen from such supplypasses through a regulator and thence, typically, via a tube to the nosewhere it is inhaled (e.g., via a nasal cannula or the like).Alternatively, the oxygen may be delivered by a cannula directly intothe trachea (transtracheal supplemental oxygen). Embodiments of thepresent invention combine the supply of oxygen or oxygen-rich air with apulse oximeter that adjusts the release of the supply to better matchthe actual bodily requirement based on the measured blood oxygensaturation. A pulse oximeter that receives the signal from the pulseoximeter probe is located a distance from the probe itself, and providesa blood oxygen saturation measurement to the user (and/or to a remotemonitor), and/or, in certain embodiments acts to adjust the inflow rateor quality of the oxygen or oxygen-rich gas being supplied. This,depending on each particular user and his/her baseline settings, caneither extend the life of a given supply of compressed oxygen oroxygen-rich gas, or provide oxygen or oxygen-rich gas on a moreaccurate, as-needed basis, in the latter case improving the healthand/or performance of the user.

As to the latter benefit of this aspect of the present invention,provision of an accurate, as-needed supply of oxygen reduces the risk ofand/or alleviates problems of hypoxia that are associated with improperadjustment of supplemental oxygen to patients in need thereof. Hypoxia,low oxygen delivery, or hypoxemia, low oxygen tension in the blood,cause a number of maladies including polycythemia (increased hematocrit)which leads to abnormal clotting. Polycythemia is a compensatorymechanism to chronic hypoxemia that typically builds up over weeks tomonths. It is typical in persons with chronic lung disease (and alsopersons living at high altitudes).

A more immediate, primary physiologic compensatory response to oxygendeficit is increased cardiac output. This is normal, such as duringincreased physical exertion. However, in persons who have impairedcardiocirculatory reserve, increased cardiac output in response to lowarterial oxygen level can, under certain circumstances, eventually leadto death. The second immediate physiologic compensatory response tooxygen deficit is the extraction of more oxygen from hemoglobin withinthe capillaries of the body's organs. This normally happens eitherduring an increase in oxygen demand (i.e., exercise, fever, shivering,etc.), or during normal demand but decreased oxygen delivery (i.e., dueto inadequate blood flow, anemia, hypoxia). In such instances,metabolically active cells draw additional oxygen from the red bloodcells which ultimately resulting in a decrease in the mixed venousblood's oxygen saturation falling from a typical 65% to 80% level tolevels as low as 32% (see Hemodynamic Monitoring—Invasive andNoninvasive Clinical Application, by Gloria Oblouk Darovic, 3^(rd) Ed.,2002, Chapter 12). Chronic hypoxemia can lead to a switch bymetabolically active cells to anaerobic metabolism, which, especially inpatients with limited cardiopulmonary reserve, can lead to lacticacidosis and eventually death.

Hypoxemia also causes cognitive dysfunction either acutely orchronically which can lead to early dementia and death. Generally, basedon the compensatory mechanisms and effects on body tissues, chronichypoxemia may affect all organs in the body leading to failure of any orall organs.

In general, blood oxygen levels are currently measured by pulseoximetry, which can be divided into transmittance and reflectance types.Transmittance, or transillumination oximetry, involves the processwhereby a sensor measures light extinction as light passes through aportion of blood-perfused tissue. Light is transmitted from one side ofa portion of blood-perfused tissue, and is recorded by a sensor situatedacross the portion of tissue. Reflectance oximetry, on the other hand,has both the light source and the sensor on one side of the tissue, andmeasures reflectance back from the tissue. For both types of oximetry,multiple signals from the light sensor, or detector, are used toestimate the oxygen saturation and pulse rate from changes in absorptionof the light detected throughout blood pulse cycles. The technology isbased on the differential absorbence of different wavelengths of lightby different species of hemoglobin.

Conventional pulse oximetry measurement in certain classes of patients,for instance severely burned patients, can be a significant challenge,yet this monitoring data is vital in operating room and intensive caresettings. Most current pulse oximetric approaches depend upon availableperipheral sites permitting transillumination oximetry which issufficient for most surgical conditions and procedures. However, in oneexample, patients with severe burns often have only a few sites suitablefor the effective placement of the transmitting pulse oximeter sensor.These patients often have severe circulatory compromise rendering thecurrent peripheral pulse oximeters less effective.

The technology of pulse oximeters is well known (See “Pulse Oximetry:Principles and Limitations,” J. E. Sinex, Am. J. Emerg. Med., 1999,17:59-66). Pulse oximetry includes a sensor, or probe, with lightsource(s) generating at least two different wavelengths of light, and adetector placed across a section of vascularized tissue such as on afinger, toe, or ear lobe. Pulse oximetry relies on the differentialabsorbance of the electromagnetic spectrum by different species ofhemoglobin. In a typical system, two distinct wavelength bands, forinstance 650-670 nm and 880-940 nm, are used to detect the relativeconcentrations of oxygenated hemoglobin (oxyhemoglobin) andnon-oxygenated reduced hemoglobin, respectively. The backgroundabsorbance of tissues and venous blood absorbs, scatters and otherwiseinterferes with the absorbance directly attributable to the arterialblood. However, due to the enlargement of the cross-sectional area ofthe arterial vessels during the surge of blood from ventricularcontraction, a relatively larger signal can be attributed to theabsorbance of arterial hemoglobin during the systole.

By averaging multiple readings and determining the ratio peaks ofspecific wavelengths, a software program can estimate the relativeabsorbance due to the arterial blood flow. First, by calculating thedifferences in absorption signals over short periods of time duringwhich the systole and diastole are detected, the peak net absorbance byoxygenated hemoglobin is established. The signals typically are in thehundreds per second. The software subtracts the major “noise” components(from non-arterial sources) from the peak signals to arrive at therelative contribution from the arterial pulse. As appropriate, analgorithm system may average readings, remove outliers, and/or increaseor decrease the light intensity to obtain a result. The results from onesite provide a measurement of arterial oxygen saturation at that site,and also allows calculation of the shape of the pulse at the placementsite of the probe, which can be developed into a plethysymograph. Amongthe various sources of signal interference and modification, it is notedthat the shape of red blood cells changes during passage througharterial and venous vessels. This change in shape affects scattering ofthe light used in pulse oximetry. Algorithms are designed to correct forsuch scattering.

More sophisticated pulse oximetry systems detect at more than merely twobands, such as the 650-670 nm and 880-940 nm wavelength bands. Forinstance, the pulse oximetry article from a uni-erlangen web site statedthat four LEDs, at 630, 680, 730 and 780 nm, each with 10 nm bandwidths,can determine the four common species of hemoglobin. The article furthercalculated that the detection of nine wavelengths in the range of 600 to850 nm would provide greater accuracy in assessing these four forms ofhemoglobin, oxyhemoglobin (O.sub.2Hb), reduced hemoglobin (HHb),methemoglobin (MetHb), and carboxyhemoglobin (COHb). As used in thepresent invention, the term “pulse oximeter” or “oximeter” is meant toinclude all designs and types of pulse oximeters, including current andlater developed models that transmit and detect at more than twowavelengths associated with absorption differences of these hemoglobinspecies.

At present, peripheral vascular resistance can only be measuredinvasively, or non-invasively by skilled technicians using Doppler flowdevices. The use of Doppler and Doppler waveform analysis is now astandard investigation technique for obtaining measurements in bloodflow resistance patients with possible circulatory disorders. Forexample, Dougherty and Lowry (J. Med. Eng. Technol., 1992: 16:123-128)combined a reflectance oximeter and a laser Doppler flowmeter tocontinuously measure both blood oxygen saturation and perfusion.

A number of patents have been issued directed to monitors, sensors andprobes for use in pulse oximetry procedures. For instance, U.S. Pat. No.6,334,065, issued on Dec. 25, 2001 to Al-Ali, et al., discloses a stereopulse oximeter that provides for simultaneous, non-invasive oxygenstatus and photoplethysmograph measurements at both single and multiplesites. The invention is directed to the detection of neonatal heartabnormalities, particularly related to defects of heart-associatedvessels, and specifically directed to Persistent Pulmonary Hypertensionin Neonates (PHHN), Patent Ductus Arteriosis (PDA), and AorticCoarctation. All of these conditions result in a flow of differentiallyoxygenated blood to different peripheral extremities. For instance, inPHHN and PDA, the blood that flows to the right hand is unaffected bythe abnormal shunt that results in less oxygenated blood flowing toother areas. Thus, comparison of oxygen saturation values between apulse oximeter sensor at the right hand and at, for instance, a footsite, is stated to detect or confirm the diagnosis of such neonatalheart abnormalities. Continuous monitoring with such pulse oximetry alsois proposed, to provide feedback on the effectiveness of treatments orsurgery to deal with these neonatal cardio/cardiopulmonary conditions.U.S. Pat. No. 6,334,065 does not address the use of two probes fordetection, confirmation, or monitoring of perfusion- andresistance-related conditions in the patient. Such conditions would notbe expected in a neonatal patient, and are instead more likely found inaging patients and in patients with certain accident conditionsunrelated to neonatal heart and heart-associated vessel anomalies.

U.S. Pat. No. 6,263,223 was issued on Jul. 17, 2001 to Shepard et al.,and teaches a method for taking reflectance oximeter readings within thenasal cavity and oral cavity and down through the posterior pharynx.Whereas the conventional transillumination pulse oximeter probe detectsthe light not absorbed or scattered as it crosses a vascularized tissuecovered by skin (i.e., the LEDs and photodetector are separated by thetissue), a reflectance oximeter probe detects light by backscattering oflight that traverses vascularized tissue not bounded by skin and isreflected back to a detector positioned on the same side of the tissueas the LEDs (e.g., on tissue in the mouth). The method includesinserting a reflectance pulse oximeter sensor into a cavity within asubject's skull and contacting a capillary bed disposed in the cavitywith the reflectance pulse oximeter sensor. The method uses standardpulse oximeter sensor probes placed over capillary beds close to abuccal surface, posterior soft palate, hard palate or proximal posteriorpharynx, including the tongue, nares or cheek. Reflectance pulseoximetry at these sites determines arterial oxygen saturation. One majorproblem with this device is that it does not permit cross-sitecomparisons of oxygen saturation values between several tissue sites. Inaddition, the pulse oximeter device used in this invention is anelongated tube that is inserted far into the nasal or oral cavity downinto the pharynx, which is a highly invasive procedure.

U.S. Pat. No. 4,928,691, issued on May 29, 1990 to Nicolson et al., andcurrently withdrawn, discloses a non-invasive, electro-optical sensorprobe and a method for its use. The sensor is enabled to measure lightextinction during transillumination of a portion of blood-perfusedtissue and to calculate the oxygen saturation and pulse rate fromchanges in absorption of the light detected. The sensor probe is placedat a central site such as the tongue, cheek, gum or lip of the patientand provides continuous assessment of arterial oxygen saturation andpulse rate. The sensor is malleable and extremely flexible, and isstated to conform to the structure of the skin and underlying tissue.U.S. Pat. No. 4,928,691 states that measurement at the preferred centralsites provide accurate oxygen saturation and pulse readings for“patients with lowered or inconsistent peripheral perfusion.”Critically, the probes according to U.S. Pat. No. 4,928,691 are highlyflexible, leading to a high likelihood that upon typical movement of thepatient there would be mal-alignment between the light source(s) andsensor, resulting in skewed, non-usable, or unreliable signals andresults. Also, there is no teaching or suggestion to compare oxygensaturation values between several tissue sites to identify,characterize, or monitor peripheral perfusion conditions in suchpatients.

U.S. Pat. No. 5,218,962 was issued on Jun. 15, 1993 to Mannheimer etal., teaches a pulse oximetry system which monitors oxygen saturationand pulse rates by sensing the blood characteristics at two or moreperipheral sites. The device includes one or more pulse oximetry probeswhich passes light through unique regions of tissue and a sensor whichdetects the amount of light passing through the tissue, and aninstrument that independently calculates oxygen saturation level withineach region. The difference in values represents how much the oxygensaturation of the first region of tissue differs from the oxygensaturation of the second region of tissue. When the difference betweenthe two values is below a set threshold, the '962 patent attributes thisto a sufficiently high probability that the value is true, and displaysan oxygen saturation value that is a function of the two independentvalues. Where there is a difference greater than a set threshold, nooxygen saturation value is displayed. Thus, the '962 patent attributessubstantial differences between two sites to be due to error, ratherthan to an indication of a problem with peripheral perfusion and/orresistance.

U.S. Pat. No. 5,335,659, issued on Aug. 9, 1994 to Pologe, teaches anasal septum probe for photoplethysmographic measurements that clipsonto a patient's nasal septum. Pulse oximetry is one of the statedapplications for the apparatus. Structurally, the apparatus disclosedand claimed in the '659 patent has a body, or housing, from which twoprobe arms extend, these arms being sized to enter the nostrils of anose. One arm bears at least two light sources, and the other arm bearsat least one light detector. The probe apparatus securely grasps thenasal septum in such a way that there is contact on both sides of thenasal septum at the same time with both the light sources and the lightdetector. In all embodiments, the light sources and the light detectoractually protrude from the main body of the respective probe arm, andare positioned to exert pressure upon and indent the tissue of the nasalseptum. In some embodiments and all claims, a supply of gas is alsoprovided from a source through a support means and to the nasal septum.However, the '659 patent does not disclose a nasal pulse oximeter probethat does not need to press into the tissue of the nasal septum in orderto obtain reliable pulse oximetry data, nor a probe that includes anangle, or bend, to reach a desired highly vascular plexus on the septum.

U.S. Pat. No. 6,144,867, issued on Nov. 7, 2000 to Walker, teaches aflexible pulse oximeter sensor assembly capable of doubling over tosurround a body part, such as an ear lobe, and comprised of a flexiblebase having a hole passing through it, a post preferably having a sharptip, and a grommet. In use the sensor assembly wraps around a body part,and the post, or pin, passes through the body part to secure the probeto the body part. The grommet frames the hole and engages and holds thepost. The patent discloses that body parts other than the ear lobe thatmay be pierced by the post (and, presumably, therefore suitable as asite for use of the sensor) include the webbing between the fingers andtoes, the tongue, the nose, eyebrows, cheek/lip, breast nipples, and theforeskin.

WIPO Application No. WO0021435A1, to Barnett et al., was published Apr.20, 2000. This publication teaches a non-invasive spectrophotometricexamination and monitoring of blood metabolites in multiple tissueregions on an ongoing and instantaneous basis. The method includesattaching multiple sensors to a patient and coupling each sensor to acontrol and processing station enabled to analyze signals conveyedthereto. The control and processing station visually displays the datafrom multiple sites for direct mutual comparison of oxygen saturationvalues from multiple sites. A key aspect of the invention is the use ofa “near” and a “far” (or “deep”) detector at each detection site. Basedon the positioning of the light-generating devices and the near and farsensors, the far sensor receives absorption signals from deeper insidethe brain tissue. In a basic configuration, the “near” sensor, ordetector, principally receives light from the source whose mean pathlength is primarily confined to the layers of skin, tissue, and skull,while the “far” detector which receives light sprectra that havefollowed a longer mean path length and traversed a substantial amount ofbrain tissue in addition to the bone and tissue traversed by the “near”detector. Other configurations indicate receptors receive signals fromsources across the entire brain cross-section. This is stated to provideinformation about, by calculation differences, the condition of thedeeper tissue, in particular the brain. The method is directed tocompare oxygen saturation values for cerebral tissue, such as comparingthe two hemispheres during surgery. The WO0021435A1 inventiondistinguishes itself from standard pulse oximetry of arteries close tothe surface of the body, and focuses primarily on analysis of deepertissues and organs. The application does not teach a method to measure“surface” peripheral or central tissue sites for development ofinformation regarding perfusion status.

WIPO Application No. WO0154575A1, to Chen et al., was published on Aug.2, 2001. This publication teaches a non-invasive apparatus and methodfor monitoring the blood pressure of a subject. A monitor is used forcontinuous, non-invasive blood pressure monitoring. The method includesusing sensors to detect a first blood pressure pulse signal at a firstlocation on patient and detecting a second blood pressure pulse signalat a second location on the patient; measuring a time difference betweencorresponding points on the first and second blood pressure pulsesignals; and, computing an estimated blood pressure from the timedifference. The first and second sensors are placed at locations such asa finger, toe, wrist, earlobe, ankle, nose, lip, or any other part ofthe body where blood vessels are close to the surface of the skin of apatient where a blood pressure pulse wave can be readily detected by thesensors, and/or where a pressure pulse wave from the patient's hearttakes a different amount of time to propagate to the first location thanto the second location.

In one regard, a superior monitor system would be able to providereal-time continuous measurements of signals that would be analyzed toprovide arterial oxygen saturation, blood pressure, and pulse rate. Asuperior monitor system would utilize at least two pulse oximeterprobes, one of which is placed at a highly perfused central tissue, suchas the lip, tongue, nares, cheek, and a second probe placed at atypically less perfused areas such as a finger or toe. Also, in somesituations, a peripheral probe may be placed at sites in or distal fromareas that may be or are affected by disease- or accident-relateddiminished blood perfusion to tissues.

An additional aspect of a superior oximeter system provides both aninflow means of oxygen or oxygen-rich gas to a patient in need thereof,and an integral or adjoining pulse oximeter probe. This aspect is inconjunction with the above-described two pulse oximeter probe system, orin a system that only has one oximeter probe. In either case, one pulseoximeter probe, positioned at the nose or mouth, detects the levels ofoxygenation saturation of blood in the patient, and detection of low orlowering oxygenation saturation levels results in one or more of:setting off a local or remote alarm or message; increasing the flow ofoxygen or oxygen-rich gas to said patient. Likewise, detection of higheror increasing oxygenation levels results in one or more of: setting offa local or remote alarm or message; decreasing the flow of oxygen oroxygen-rich gas to said patient. Preferably, the pulse oximeter probe atthe nose or mouth is integral with the delivery means of the oxygen oroxygen-rich gas. Preferably, the control of oxygenation levels is bysignaling to (manually or automatically) adjust a valving mechanism thatcontrols output flow from a source of auxiliary of oxygen or oxygen-richgas. By such feedback mechanism the quantity of oxygen or oxygen-richgas is conserved, and the needs of such patient are more closely attunedto the fluctuations in oxygen demand during activities at varying levelsof exertion during a period of time.

As to references that pertain to the combining of a pulse oximeter witha system to control the inflow of oxygen or other oxygen-rich gas to apatient in need thereof, the following U.S. patents, and referencescontained therein, are considered to reflect the state of the currentart: U.S. Pat. Nos. 4,889,116; 5,315,990; 5,365,922; 5,388,575;6,371,114; and 6,512,938. None of these references are specificallydirected to a combined, preferably integral combined pulse oximetersensor/nasal cannula, which, when combined with an oximeter, or with anoximeter that controls the inflow of such oxygen or other oxygen-richgas to the patient, provide the advantages disclosed and claimed herein.

All patents, patent applications and publications (scientific, lay orotherwise) discussed or cited herein are incorporated by reference tothe same extent as if each individual patent, patent application orpublication was specifically and individually set forth in its entirety.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a novel non-invasivevascular perfusion/resistance monitor system having at least two pulseoximeter probes positioned at locations on the body of a patient, thesignals from which may be capable of indicating a problem withperipheral perfusion and/or resistance. In practice each probe emits atleast two different light frequencies, such as by light-generatingdiodes (LEDs), and such emitted light is detected by at least one lightdetector, such as a photodiode detector. A general-purpose computer or aspecial purpose computer is employed to perform complex mathematicalcomputations based, typically, on the signal intensity and timing fromthe at least two pulse oximeter probes, and on signals from the lightdetectors of each of the probes. Proper analysis by software programmingin such general-purpose computer or special purpose computer outputsresults to a display, printer, etc. that suggests or indicates(depending on relative differences in the signals at differentlocations, and upon other conditions) whether a condition of diminishedor abnormal vascular perfusion/resistance may exist in a selected bodyarea. The system also monitors changes in such conditions duringtreatment interventions.

In a preferred embodiment, software programming provides for a signal toa user of the device to alert the user when signals from a central or anon-central probe are of such low pulse amplitude that either the probeneeds repositioning or that the patient is experiencing extremely lowpulse at the probe site (and is therefore in need of acuteintervention). The software program also converts the signals from thelight detectors to calculate various oxygen saturation values andvarious blood pressure values (either simultaneously or separately).These values are used for evaluating the vascular perfusion/resistanceand/or blood pressure of a patient based on the locations of the two ormore probes.

Each probe is designed for monitoring blood oxygen saturation and/orblood pressure at different vascular bed sites on a patient. Critically,one of the at least two sites on a patient is at what is designated a“central source” site (“CSS”). The inventors have discovered that flowdirected through the carotid artery and detected at CSS sites, such asthe lip, tongue, nasal nares, and facial cheek, are typically strong andunaffected by perfusion-lowering conditions. In patients who do not haveperfusion-lowering conditions, a second or third probe site at“non-central” site (NCS), such as an extremity (i.e., fingers, toes,etc.), provides oxygen saturation and pulse values fairly comparable tovalues from the CSS. However, when a patient has a perfusion-loweringcondition, the probe site at an affected extremity provides noticeablydifferent oxygen saturation and pulse values compared to the CSS values.The difference in saturation values between the CSS and one or moresites is then used to assess peripheral vascular resistance, perfusionand/or peripheral vascular disease.

As used in this disclosure, when a particular wavelength or band ofwavelength is stated at which an LED or other light-generating sourceemits light, it is understood that such light-generating source may andprobably does emit light across a broader range. However, what is meantby such statement is that such light-generating source is designed toemit at a frequency curve which has a peak at or near such statedwavelength or band. It is further understood that any known means oflimiting non-desired light energy, such as by selective filtration, maybe used in conjunction with such light-generating sources to improve theaccuracy and/or precision of the emissions of such light-generatingsources.

As used in this disclosure, a “pad” is meant to indicate a housing, oran enclosure, over a light-generating or a light-sensing device on theprobe, which provides a barrier to fluids, and permits transmission oflight of the relevant wavelengths to the present invention. A typicalpad has a composition of clear plastic.

As used in this disclosure, a “conductor” is meant to indicate anyphysical pathway or any system that communicates a signal or electricityfrom a first to a second location. Signals and electricity can beconducted by conventional means, such as by sending electrical impulsesalong a continuous copper wire, by more sophisticated means, such as byconverting the signals into radio waves and transmitting these wavessuch that a receiver receives the signals and thereafter sends them tothe controller, or by any other way now known or later developed.

As used in this disclosure, whether or not so stated in a particularsentence, the term “oxygen” may be taken to mean “oxygen or anyoxygen-rich air or other gas mixture that contains oxygen” which is usedfor provision of oxygen to a patient or to a person in need thereof. Thecontext of a particular usage in this disclosure indicates whether thisbroader definition is to be used, or whether a particular example isreferring instead to the use of pure oxygen exclusively.

While some researchers have attempted to gauge accuracy by comparing theresults from two different pulse oximeter probe sites (see U.S. Pat. No.5,218,962), and other researchers generally recognized that “central”sites are generally more reliable and responsive than “peripheral” sites(see U.S. Pat. Nos. 6,263,223, and 4,928,691), the present inventionrecognizes the reasons for the inconsistently different results betweenCSS and non-CSS sites. Specifically, patients having compromisedperipheral circulation and/or resistance will tend to have lowerperipheral values than patients without such compromised conditions. Bysuch recognition, detection and monitoring impaired peripheralcirculation is possible through the present disclosure. The monitoringsystem of the present invention, in certain embodiments, additionallyprovides an indication of vascular resistance through continuousmonitoring of the transit time difference of the blood oxygen saturationvalues and the blood pressure values between the two sites.

It is an object of the present invention to provide a monitoring systemwhich includes two pulse oximeter sensors, or probes, connected to amonitor system as a non-invasive means for continuously measuring bloodoxygen saturation values and/or blood pressure and/or pulse values,wherein the system detects and monitors changes in vascular perfusionand resistance in a patient. The overall system particularly assessesdifferences in peripheral blood flow which may be impaired in certainillnesses and accident conditions.

Another object of the present invention is to provide probesfunctionally constructed to provide more reliable signal reception andtransmission for patients, such as those in ICU, surgery, post-operativecare, and patients with respiratory, circulatory problems, or underanesthetics. In particular, pulse oximeter probes are configured to beplaced, respectively, across the lip or cheek, in the nostrils of thenose, and on the tongue.

Thus, one object of the invention is to provide a novel configuration ofan oximeter probe that is well-suited for placement across the lip ofthe mouth of a patient, or the cheek of a patient, in which one side ofthe probe is situated outside the oral cavity and a second side ispositioned inside the mouth cavity, and the tissue between the two sidesis assessed by transillumination pulse oximetry. Another object of theinvention is to combine the probe for placement across the lip or cheekof the present invention with sampling devices for capnography sampling,either with or without a structure or assembly for the supply of oxygen,as from a cannula. Another object of the invention is to combine withthe probe for placement across the lip or cheek a disposable cover toslip over the probe.

Still another object of the present invention is to utilize thephotoplethysmographic data obtained from the probes of the presentinvention for diagnosis and monitoring of clinical conditions.

Another object of the invention is to provide a novel configuration ofan oximeter probe that is well-suited for placement at the nasal cavityof a patient, in which one side of the probe is situated to the leftside of the nasal septum, and a second side is positioned to the rightside of the nasal septum, and the tissue between the two sides isassessed by transillumination pulse oximetry. This design, in apreferred embodiment, also functions to provide oxygen to the patientthrough channels provided in the structure of the probe. The embodimentsof the nasal probe of the present invention advance the art by obtainingreliable and repeatable pulse oximetry and plethysmography data from theinterior nasal septum with the extensions going into the nose beingdesigned and spaced so as to not press into the tissue of the septum.Further, the extensions of the probe, where the light-generating and thelight-detecting components are positioned, do not simultaneously contactthe respective areas of mucosal tissue of the nasal septum. Thisprovides a more comfortable probe than the prior art that,advantageously, does not impair blood flow in the vascular tissue beingevaluated, and does not harm that tissue as may occur from a probe thatexerts simultaneous pressure from both sides.

Another object of the invention is to combine the nasal probe of thepresent invention with sampling devices for capnography sampling, eitherwith or without a structure or assembly for the supply of oxygen, asfrom a cannula. Another object of the invention is to provide a novelconfiguration of an oximeter probe that is well-suited for placement onboth sides of either the right or the left nasal alar (i.e., the alarnari). One side of the probe is situated to the outside of the nasalnari, and a second side is positioned to the inside of the nasal nari,and the tissue between the two sides is assessed by transilluminationpulse oximetry.

Another object of the invention is to provide a novel configuration ofan oximeter probe that is well-suited for placement on the tongue of apatient, in which one part of the probe is situated along one surface ofthe tongue, and an opposing part is positioned in such a manner as tocapture a section of the tongue such that a transilluminablecross-section of tongue tissue is held between the two probe parts, andthe tongue tissue between the two probe parts is assessed bytransillumination pulse oximetry.

It is another object of the present invention to provide pulse oximeterprobes dimensioned and configured to be expandable, spring-loaded, andflat surfaced for utilizing measurements on extremities and earlobes;buccal mucosal-buccal surface or dorsal ventral portion of the tongue;and properly sized configurations for the nasal alars (i.e., alar nares)and cheek and/or tongue for critically ill, burned, or traumatizedpatients. A related object is to provide a configuration for an oximeterprobe that utilizes two opposed, substantially flat probe surfaces thattend toward each other, such as by spring tensioning.

It is a further object of the present invention to provide a monitoringsystem that measures vascular resistance and/or perfusion continuouslyto improve volume resuscitation and/or drug therapy.

It is still a further object of the present invention to provide amonitoring system that can be used as a multi-probe pulse oximeter tomonitor blood oxygen saturation differences, pulse transit timedifferences, or blood pressure, or any combination thereof.

It is still another further object of the present invention to providespecifically constructed probes used to transmit and receive the lightto vascular bed sites that are not normally available for use due toburns, trauma, and surgery on the extremity.

It is still another further object of the present invention to provide amonitoring system that is easily fabricated from low cost material andis adaptable for use in an operating room, intensive care unit,emergency room or other areas to treat patients in need of hemodynamicmonitoring.

Still another object of the present invention is to provide a pulseoximeter probe and a supply of oxygen or oxygen-rich air, incombination, and functioning in concert with each other and withoximetry circuitry, such that the level and trend in blood oxygensaturation are determined by the pulse oximeter and changes in bloodoxygen saturation direct a change (i.e., an increase or a decrease) inthe release of oxygen or oxygen-rich air to the patient whose bloodoxygen saturation is being measured. In one type of control of the flowof oxygen or oxygen-rich air, an electronic regulator is controlled bysignals from a processor that receives data from the pulse oximeter.

Thus, one particular object of the present invention is to integrate anovel nasal pulse oximeter probe of the present invention with a nasalcannula. Another particular object of the present invention is tointegrate a pulse oximeter probe with either a self-container breathapparatus (SCBA) or with the regulator of a self-contained underwaterbreathing apparatus (SCUBA). Blood oxygen measurements obtained by theso integrated pulse oximeter probe then are used to regulate thepercentage oxygen in the supply of gas to the user, and/or to regulatethe flow rate to the user upon inhalation. In the case of a SCBAapparatus that is combined with a pulse oximeter probe and oximeter,where that mask is worn in environments with toxic or noxiousatmospheres, a critical role of the sensor is to indicate to the userwhen they are becoming hypoxemic, i.e. when there are potentiallydangerous gases leaking into the mask. In the case of a SCUBA apparatusthat is combined with a pulse oximeter probe and oximeter, for any divethe oximeter can provide information related to the formation of an airembolus. For deep dives, where specialty mixed gases are used and oxygenconcentration in such mixtures are actually reduced from itsconcentration in air, the oximeter data on blood oxygen saturationprovides a warning of current or pending hypoxemia. When furthercombined with a control to adjust the relative concentration of oxygento other gases, this device serves to increase the relative oxygenconcentration delivered to the diver when the oximeter data trend soindicates the need.

Still another object of the present invention is to provide a pulseoximeter probe and a supply of oxygen or oxygen-rich air, incombination, and functioning in concert with each other and withoximetry circuitry, such that the level and trend in blood oxygensaturation are determined by the pulse oximeter and changes in bloodoxygen saturation that indicate a sufficient downtrend in the bloodoxygenation status results in a local or remote alarm to alert thepatient and/or others to the problem.

Still another object of the present invention is to utilize thephotoplethysmographic data obtained from the probes of the presentinvention for diagnosis and monitoring of clinical conditions.

The foregoing has outlined some of the more pertinent objectives of thepresent invention. These objectives should be construed to be merelyillustrative of some of the more prominent features and applications ofthe invention. Many other beneficial results can be attained by applyingthe disclosed invention in a different manner of modifying the inventionas will be described.

It is to be understood that the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not to be viewed as being restrictive of the present, as claimed.These and other objects, features and advantages of the presentinvention will become apparent after a review of the following detaileddescription of the disclosed embodiments and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a hook-shaped pulse oximeter probeshowing a preferred positioning of a LED pad having two LED's and atleast one photodiode detector according to the present invention. Thisprobe is configured for positioning across the lip or cheek of apatient.

FIGS. 2A-C provide top, front, and cross-sectional views, respectively,of a pulse oximeter probe for positioning in the nares of a nose of apatient. Connecting wires are shown in schematic format, not to scale.FIG. 2D provides an enlarged view of one area of FIG. 2A. FIG. 2Eprovides a perspective view of a protective sheath used to cover thepulse oximeter probe of this figure. FIG. 2F provides a front view of analternative embodiment of a nasal probe with a widened area toaccommodate the size of the nasal columella. FIG. 2G provides across-sectional view of the alternative embodiment of FIG. 2F.

FIG. 3A-B depicts a side view and a top view of a pulse oximeter probefor positioning on the tongue of a patient.

FIG. 4 illustrates a perspective angled side view and an explodedfrontal cross-sectional side view of a flat surfaced, elongatedspring-loaded pulse oximeter probe showing the configuration of theLED's and the photodiode detector according to the present invention.

FIG. 5 illustrates an internal view of the pulse oximeter sheathaccording to the present invention.

FIG. 6 illustrates a perspective angled side view of a flat surfaced,elongated spring-loaded pulse oximeter probe showing the features of thepulse oximeter sheath according to the present invention.

FIG. 7 is a flow chart showing one method utilized by the non-invasivevascular perfusion/resistance monitoring system to measure oxygensaturation values according to the present invention.

FIGS. 8A and 8B provide front and side views, respectively of a novelcombined nasal pulse oximeter probe/oxygen cannula.

FIG. 9A provides a side view of a typical self-contained underwaterbreathing (“SCUBA”) apparatus typical of the prior art apparatuses. FIG.9B provides a side view of a SCUBA apparatus of the same configuration,with a cross-lip pulse oximeter sensor added to this apparatus.

FIG. 10 provides a schematic flow diagram for control signaltransmission from a pulse oximeter sensor to a control circuit to anoxygen control valve being controlled by data output from the sensor,where the control valve regulates oxygen to a patient wearing thesensor.

FIG. 11 provides a diagrammatic profile of a human subject indicatingthe angle of the upper lip, and how this affects the positioning of anasal probe of the present invention.

FIGS. 12A-15B display data from a comparison of positions on the nasalinterior septum of one volunteer subject, indicating the difference insignal strength and quality when the nasal probe is positioned to obtaindata through a vascularized plexus identified as Kiesselbach's plexus.

FIGS. 16A-C display data from a volunteer subject in which three pulseoximeter probes were evaluated and compared—one at the nasal interiorseptum, one at the cheek/lip, and one at the finger.

FIGS. 17A-C display data from three different volunteer subjects, all ofwhom, during a surgical procedure, experienced arrhythmias that weredetected differentially by the three probes being evaluated and compared(one at the nasal interior septum, one at the cheek/lip, and one at thefinger). FIG. 17D provides a comparison of the three probes in theirability to detect a dicrotic notch.

FIG. 18A-C displays data from a nasal probe on one volunteer subject,where the position of the probe was adjusted to three differentpositions. FIG. 18D depicts a side view sketch of a profile of a subjectwith an alternative nasal probe design that reaches to a desiredlocation for obtaining data.

FIG. 19A is a plan/cut-away view of a nasal probe of the presentinvention in combination with a known design of a capnographysampling/oxygen supply device. FIG. 19B is a perspective diagrammaticview of an embodiment, in place on a subject, of the combination devicedepicted in FIG. 19A.

FIG. 20 is a side view of a lip/cheek in combination with a design of acapnography sampling/oxygen supply device.

DETAILED DESCRIPTIONS OF EMBODIMENTS

The present invention discloses pulse oximeter probes for use with pulseoximeter systems in general. The present invention also discloses anovel non-invasive vascular perfusion and/or resistance status monitorapparatus and methods of using the same.

FIG. 1 illustrates a pulse oximeter probe, 10, of the invention, that isconfigured for placement with a section of the probe placed inside themouth for measurement across the vascularized tissue of the lip orcheek. The probe, 10, as depicted in FIG. 1, is comprised of a framethat is generally hook-shaped, having a longer proximal arm, 1, a curvedbridging section, 2, and a shorter distal arm, 3, the latter arm havinga free end, 4, that enters the mouth when in use. At least one portionof the proximal arm, 1, is positioned at a specified distance, 5, froman opposing portion of the distal arm, 2, to provide a distance betweenthe closest points of the two opposing arms, 6, that accommodates thethicknesses of the lips and/or cheeks of a desired range of patients. Asshown in FIG. 1, the opposing portions of the proximal arm, 1, and thedistal arm, 2, that are the specified distance, 5, represents most ofthe lengths of these arms. In other embodiments of this probe, a smallerpercentage of the total span of opposing arm sections may be set to suchspecified distance.

The probe may be used once and disposed, or may be repeatedly used ondifferent patients. Preferably, the probe frame is constructed ofmetals, plastics, and other materials subjectable to repeated cleaningwith standard antiseptic solutions, or sterilizable by other means. Acable, 7, houses conductors (not shown), such as but not limited toinsulated electrical wires, that connect operative components further inthe probe, 10, with an oximeter monitor (not shown). A boot, 8, connectsthe cable, 7, to the proximal arm, 1, of the hook-shaped frame of theprobe 10. Preferably the cable, 7, is flexible. The boot, 8, primarilyserves to connect the cable, 7, with the frame, and secondarily toprovide a handle with which the patient or attendant grip the probe. Inother designs of the lip/cheek probe, a boot is not required where adirect connection is made between the cable and the frame of the probe.

In the embodiment depicted in FIG. 1, the probe 10 comprises two LEDs 17within an LED pad, 12, and one photodiode detector 15 within aphotodetector pad, 14. These are the operative components of the probe,10, and are connected to a monitor system (not shown) by conductors (notshown) to transmit electrical signals. It is noted that although the twoLEDs, 17, are shown as two physically separate components in FIG. 1,when present on a circuit board, typical LEDs are very small (about thesize of a pencil point), yet discrete components. Thus, the two LEDsalternately can be represented as both being present on a singlestructure in other figures.

Each probe 10 is sized appropriately to be placed with the open end, 4,inside a patient's mouth, so that the distance, 6, between the LED pad,12, and the photodetector pad, 14, conforms to the thickness of the lipor cheek vascular bed of the patient. It is noted that FIG. 1 is notaccurately drawn to scale, and given the true small size of the pads 12and 14, the actual difference between the distances 5 and 6 is less thanabout 0.5 inches. In practice, one probe 10P (not shown) is sized forthe average pediatric patient, age 6-12, and another probe 10A (notshown) is sized for the average adult patient.

The embodiment depicted in FIG. 1 has the light-sensing device, such asthe photodiode detector, 15, positioned in the mouth, on the side withthe open end, 4, as shown in FIG. 1. Having the light-sensing device onthe inside side of the cheek or lip minimizes erroneous readings due tointerference from ambient light sources. Such light sources are muchmore likely to affect a light-sensing source that is positioned on theoutside side of the cheek or lip. However, having the light-sensingsource positioned on the outside side of the cheek or lip is within thescope of the invention.

Individual conductors provide electrical signals that power the LEDs 17.Other conductors carry signals from the photodetector, 15. Optionally,other sensors, such as for temperature, may be added to the probe, 10,and have individual conductors for them also passing in the cable, 4, tothe frame of the probe, 10. The probe, 10, is used to generate data usedto calculate oxygen saturation, pulse shape, blood pressure measurement(by measurement of pulse transit time to a second site), and anycombination of these.

The bridging section, 2, flexes to permit conformance to a range oftissue thicknesses greater than the nominal unflexed spans, as depictedby distances 5 and 6. The probe in FIG. 1 preferably is constructed ofmaterials, such as nylon plastic, that impart a resiliency such thatafter bending, the probe returns substantially to its original shape.This resiliency allows the angular and dimensional relationships betweenthe light-generating sources and the opposingly placed light detector toremain substantially consistent. Thus, the material for one embodimentof the probe has a degree of flexibility, and the material hassufficient memory to substantially return to its original shape after anormal flexion. This allows for standard use that may involve placementacross lip and cheek tissue sections having different thicknesses, andmovement across a thicker tissue section to ultimate placement at athinner section.

For instance, in one embodiment of this configuration, the body of theprobe, 10, is made of nylon plastic. The flexibility of the bridgingsection, 2, the proximal arm, 1, and the distal arm, 3, is such thatless than 5 grams of force deflects the open end, 4, in one direction orthe other (toward or away from the opposing section) by about 1/16 inch.The force required increases logarithmically, such that to move the openend, 4, outwardly 0.25 inch required between about 1,250 to 1,550 gramsof force, and the force required to move the open end, 4, inwardly(toward the opposing section) required between about 2,200 to 2,700grams of force. After such forces the nylon material demonstratedmemory, returning to within 1/16 inch of the original position, thusdemonstrating a resilient quality to the structure of the probe.

In addition, the material of each of the LED pad, 12, and thephotodetector pad, 14, deflects upon application of pressure fromadjacent tissue by up to about 0.050 inch. Thus, the overall flexibilityis sufficient to accommodate a wide range of sizes of cheek and lipsections, which the axis of light transmission from the LEDs is reliablyaligned to the photodiode or other light sensor. While not being boundto a particular theory, it is believed that maintaining appropriatelynarrow alignment of these elements improves the reliability, precisionand accuracy of the signals from the probe.

More flexible probes are alternate embodiments of the present invention.For instance, the structural material and thickness is adjustable suchthat only between about 150 to 1,250 grams of force moves the open end,4, outwardly 0.25 inch, and between about 200 to 2,200 grams of forcethe force moves the open end, 4, inwardly (toward the opposing section).

Less flexible probes also are alternate embodiments of the presentinvention. For instance, the structural material and thickness isadjustable such that between about 1,550 to 3,500 grams of force movesthe open end, 4, outwardly 0.25 inch, and between about 2,700 to 5,000grams of force the force moves the open end, 4, inwardly (toward theopposing section). Alternately, in a more rigid probe, the structuralmaterial and thickness is adjustable such that between about 3,500 to5,500 grams of force moves the open end, 4, outwardly 0.25 inch, andbetween about 5,000 to 8,000 grams of force the force moves the openend, 4, inwardly (toward the opposing section). Such probes are made ofmetals or polymer composite materials. The resiliency is expected tovary inversely, roughly, with the flexibility of probes of suchalternative embodiments.

Although in FIG. 1 the bridging section, 2, is curved, other embodimentsof this lip/cheek probe may have a bridging section of any shape andangle, so long as it spans a distance and connects the opposing sidesupon which the operative components of the probe are placed. Further, asto all lip/cheek probes of the present invention, it is noted that thedimensions, materials and structures of such probes provide formaintaining a desired position on the lip or cheek of a patient, suchthat the insertion of a post, or pin, through the lip or cheek, so as toretain such desired position of the respective probe, is not required.

FIG. 2A-D illustrates a second pulse oximeter probe, 50, of theinvention, that is configured for placement inside the nostrils of thenose for measurement across the vascularized tissue of the nasal septum.The nasal septum generally is defined as the bone and cartilagepartition between the nasal cavities, or the dividing wall that runsdown the middle of the nose so that there are normally two sides to thenose, each ending in a nostril. As used herein, the term nasal septum iscomprised of at least two parts. A columella nasi (“exterior septum” or“columella”) is defined as the fleshy lower margin (termination) of thenasal septum at the opening of the nose (i.e., the nostrils or nares). Amore interior part, broadly termed herein the “interior septum,” extendsinteriorly from the columella and is comprised of the cartilaginous andbony part of the septum. Along this interior part of the nasal septum isfound the vascularized tissue of the nasal septum, including certainhighly vascularized areas. In most noses, the columella, or exteriorseptum, is the widest part of the nasal septum.

FIG. 2A is a top view, FIG. 2B is a side view, and FIG. 2C shows twocut-away views from a single mid-section line viewing opposite ends ofthe probe. From a main section, 52, of a resilient plastic housing,extend two extensions, 54 and 56, that are sized to enter the nares ofthe nose in similar fashion to a nasal cannula oxygen supply. Theseextensions, 54 and 56, are flattened in one dimension, as depicted inFIGS. 2A and 2B, and are shown angled at about 60 degrees in a seconddimension, as viewed in FIG. 2C. This angle of inflection, 70, isproperly drawn from a line drawn from one edge of the main section, 52.As discussed in greater detail below, the 60 degrees as depicted is notwithin the preferred range.

In specific embodiments depicted herein, two general approaches are usedto protect the components of the pulse oximeter probe, 50, from moistureand contamination. Other approaches, as known in the art of medicaldevice construction, also may be used. First, a clear plastic covering,shown as 61 in FIGS. 2A and 2B, and better viewed in FIGS. 2C and 2D, isplaced over, to cover, each distal half of the two extensions, 54 and56. It is noted that in the embodiment shown, the molded outer shell,69, that forms and covers the main section, 52, also covers theapproximately proximal half of the two extensions, 54 and 56, and theouter side of the upper, or distal halves of these extensions, but doesnot cover the front and rear sides, nor the inner sides, 65, of theseextensions. To cover these exposed sides, a clear plastic covering, 61,is constructed, fitted over, and adhered to the existing components toform an integral protective exterior surface with the molded outershell, 69. This is viewable in FIGS. 2C and 2D. Such plastic covering,61, typically is manufactured by heat sealing pre-cut and/or pre-formedpieces, such as a cylinder or tube of heat-shrink plastic, to form afitted covering over the distal halves of extensions 54 and 56. Thenthis is shrink-wrapped over the components of the distal half of the twoextensions, 54 and 56. In the present embodiment, as depicted in FIG.2A-D, after heat-shrinking a cylinder of heat-shrink plastic, 61, overeach of the two extensions, 54 and 56, the distal end of this plastic isglued together to forms an end, 61E, over the distal end of each of thetwo extensions, 54 and 56. These ends, 61E, are viewed in FIG. 2C.

Also, typically these pieces of heat-shrink wrap plastic, 61, are sizedand positioned to extend onto the approximate bottom half of twoextensions, 54 and 56, by about 1/16 inch, to form an integral sealagainst moisture (this overlap is shown at arrow X in FIGS. 2C and 2D).(It is noted that neither these nor other figures are drawn to scale,nor do they provide consistent proportions from figure to figure). Inparticular, FIGS. 2C and 2D show that a plastic cover, 61, is fittedover each of the circuit boards, 63, that contain the LEDs 62 and 64,located on extension 54, and the photodetector, 66, located on extension56 (see FIG. 2C for details of LEDs 62 and 64, and photodetector 66).The plastic covers, 61, preferably do not interfere with lighttransmission in the critical wavelength ranges of the LEDs 62 and 64.Apart from heat-shrink sealing, other means of attaching the plasticcovers, 61, to the extensions 54 and 56, include, but are not limitedto, sonic welding, spot gluing, hot gluing, press fitting, and othersuch methods of attachment, as are employed in the art, that are used toattach components of a medical device for entry into an orifice of aliving subject. Also, other means of providing a protective covering,such as are known to those skilled in the art, may be used instead ofthe above-described approach.

The above-described first protective approach is sufficient to preventmoisture and contamination of the components within the distal halves ofthe two extensions, 54 and 56. A second approach, which is an optionaland not required for the operation of the pulse oximeter probe, 50,provides additional protection to this and other parts of the pulseoximeter probe, 50. This is shown in FIG. 2E. A protective sheath, 75,of clear plastic, is dimensioned to slip over the entire two extensions,54 and 56, and then has flaps, 76, that loosely cover the main section,52. The protective sheets are manufactured and priced so as to bedisposable, so that after each use by a patient the protective sheath,75, is slipped off the pulse oximeter probe, 50, and disposed of. Thenthe exterior surfaces of the pulse oximeter probe, 50, are wiped withalcohol or other suitable disinfectant. Then, prior to the next use, anew protective sheath, 75, is slipped over the indicated parts of thepulse oximeter probe, 50. Alternatively, the protective sheath, 75, ismade of a material that will withstand repeated rigorous disinfectionprocedures (such as steam autoclaving) without deformation ordegradation, such as is known in the art, and such protective sheathesare used on numerous patients, with a disinfection process conductedbetween each use.

In certain embodiments, the two extensions, 54 and 56, are spaced apartfrom one another so that, upon insertion into the nostrils of a patient,the inner sides, 65 of the extensions, 54 and 56, fit snugly against thetissue of each side of the septum, to avoid interference from ambientlighting.

Moreover, in certain embodiments, the relationship between the innersides, 65, and the adjacent tissue of the interior septum is describedas A non-contiguous fit as to the interior septum wall, such that, evenconsidering irregularities of the nasal interior septum surface andpatient movement, the inner sides, 65, do not make contact with thenasal interior septum mucosal tissue for most, or for all, depending onthe patient, of the length of the respective extension's insertion intothe nasal passage.

More particularly, a non-contiguously-fitting probe (such as 50, and itsextensions, 54 and 56) is sized and constructed so that when placed intoa nose size for which it designed (i.e., adult size, etc.), there is nota pressing or a continuous contact against the mucosal tissue of theinterior nasal septum by both extensions where are positioned thelight-generating components (such as LEDs 62 and 64) and the lightdetecting component(s) (such as photodetector 66). This contrasts withprior art that is disclosed to provide a continuous, even if light,pressure upon both sides of the interior nasal septum mucosal tissue,and/or that clips the probe against the mucosal tissue of the interiorseptum. Also, as to construction compared with the latter prior artexample, the dimensions, materials and assembly of the present inventionare such that there is not imparted to the two extensions, 54 and 56, aninward-flexing compressive force that causes attachment (as contrastedwith incidental and/or partial contact) of the two extensions, 54 and56, to the mucosal tissue of the nasal interior septum. Even moreparticularly, in part to avoid the possibility of irritation of themucosal tissue of the interior septum walls, further, in certainembodiments, the entire surface of the inner sides, 65, from the innerfaces, 67 (of the molded outer shell, 69) to the distal end of eachextension, is planar and without any protruding areas, sections orcomponents.

As to an example of the relative sizing between the thickness of thenasal interior septum and the span, 70, between the inner sides, 65, ofopposing extensions, 54 and 56, FIG. 2D provides a diagrammaticrepresentation. For an adult-sized nasal probe of this configuration,the span, 70, is 0.360 inches (9.1 mm) between the inner faces ofextensions, 54 and 56. This is uniform inward, to and including wherethe LEDs 62 and 64 of extension 54, lie opposite the photodetector 66,of extension 56. Measurements of the interior septa of a number ofadults with a caliper provides an average of about 0.250 inches septumthickness. The difference between 0.360 and 0.250 inches provides asufficient gap to allow for the presence of deviated septa. Also, it hasbeen found that this gap of 0.360 inches is sufficiently narrow so as tonot allow ambient light, under normal circumstances, to impair theoverall functioning of the pulse oximeter probe. Thus, for a typicaladult-sized nasal probe of the present invention, a space of about 0.065inches on each side, between the surface of the inner face, 67, and themucosal tissue of the nasal interior septum has been found to provide a“non-contiguous fit.”

Further, in certain embodiments of the present invention, the spacebetween inner sides, 65, of opposing extensions 54 and 56, where thelight-generating and the light-detecting components are positioned, foradult-sized probes, is between about 0.300 and 0.420 inches. In otherembodiments, for such adult-sized probes, the space is between about0.330 and 0.390 inches. In other embodiments, for such adult-sizedprobes, the space is between about 0.350 and 0.370 inches. Correspondingsize ranges are within the skill of the art to determine forpediatric-sized nasal pulse oximeter probes comprising a non-contiguousfit, based on the measured thickness of the nasal interior septum forsuch pediatric patients, and the range of spacing given factors ofcomfort and probable incidence of ambient light interference(recognizing, for instance, that neonates have greater lighttransmission through their tissues).

In certain embodiments support for the distal ends of the inner sides,65, generally is through contact with columella. This fleshy tissueextends laterally, to various extents in different individuals, from aplane generally defined by the surface of the more interior mucosallining of the interior septum. The columella is less sensitive and lesssubject to damage by direct contact than that more interior mucosallining of the interior septum. Thus, in embodiments such as thatdepicted in FIG. 2A-D, having substantially parallel inner sides, 65,when opposing parts of the respective inner sides, 65, fit snuglyagainst the columella (i.e., the inner faces, 67, of the molded outershell, 69), this helps position the more distal sections of theextensions to minimize or prevent continuous contact between these moredistal sections and the interior septum mucosal lining. Also, when aparticular patient's columella is being compressed by both inner faces,67, this results in less pressure by any incidental contact by a moredistal section of one or the other extension against the interior nasalseptum mucosal lining. Without being bound to a theory, it is believedthis is because the more outward section of that extension is in contactwith and is being partially supported by the columella. Based on suchanalysis, contact of the nasal probe extensions, on one or both of thecolumellae, is less damaging to the patient than prior art devices thatactually clamp to the more interior mucosal lining of the nasal interiorseptum.

Thus, when the extensions 154 and 156 fit snugly against the columella,and are not found uncomfortable over time by the user, this comprisesone example of a good fit. Further, such bracing contact with tissue ofthe columella is not mutually exclusive with the fit described asnon-contiguous. That is, in many uses, the same embodiment both contactsthe columella with its extensions and, more interiorly, there is not apressing or a continuous contact against the mucosal tissue of theinterior nasal septum by both extensions where are positioned thelight-generating components (such as LEDs 62 and 64) and the lightdetecting component(s) (such as photodetector 66). More broadlyspeaking, the same embodiment may both 1) provide a beneficial fitagainst the columella and 2) provide a non-contiguous fit moreinteriorly.

However, it has been observed that certain larger columellae, in certainpatients, deviate outward the extensions of the nasal probe such thatthe distal ends of the two extensions, respectively bearing thelight-generating and the light-detecting components, are positioned anundesirably long distance from each other. To deal with this, in othercertain embodiments, each of the inner faces of the extensions comprisea deviation in the shape of the extension to allow for a relativelylarger-sized columella. This is advantageous for persons having largecolumellae, so that their columellae do not force the extensions tospread outwardly to an undesirable distance from the interior nasalseptum. In such embodiments, depending on the sizing of the nasal probe(see below) and the size of the patient's nose and columella, theremight be no contact with the columella, in which case the support forthe weight of the extensions is on the part(s) of the probe main sectionthat is in contact with the upper lip. Where, given the respective sizesof probe and columella, there is contact, with such accommodation forthe columella the spreading of the ends of the extensions is less thanit would be otherwise.

FIG. 2F provides a side view, comparable with the view of FIG. 2B, ofone embodiment of the nasal probes of the present invention thatcomprises a deviation in the shape of the extensions to allow for arelatively larger-sized columella. For an adult-sized nasal probe ofthis configuration, the maximum span, 110, is 0.500 inches (12.7 mm)between the inner faces of extensions 54 and 56. This is where the nasalprobe main section, 52, and the two extensions, 54 and 56, meet, and thewider span is generally aligned to accommodate the width of thecolumella upon insertion of the nasal probe to its operational position.Further distal on the two extensions, 54 and 56, where the inner sides,65, are shown in substantially parallel orientation, are found the LEDs62 and 64 of extension 54 positioned opposite the photodetector 66, ofextension 56. Along this substantially parallel length the span betweenthe inner sides, 65, is 0.360 inches. This is shown as gap 70. Althoughthis columella-widened embodiment in FIG. 2F is shown without a cannula,and without means for sampling exhaled gas for capnography, embodimentsof nasal probes with such capabilities and features (discussed, infra)also may have a columella-widened aspect such as depicted in FIG. 2F.

FIG. 2G provides a cut-away view of FIG. 2F, showing a conduit, 82,within which are electrically conductive wires (or other types of signaltransmission means, such as fiberoptic cable) to pass electrical signalsto and from the two light-emitting diodes, 62 and 64, and the opposingphotodetector, 166. Also apparent is the angle, or inward inflection, ofthe substantially parallel lengths of the two extensions, 54 and 56. Abend such as this, as discussed herein, achieves placement of the twolight-emitting diodes, 62 and 64, and the opposing photodetector, 166,adjacent to a vascularized region of the nasal septum thatadvantageously provides superior pulse oximetry data.

Further, it is recognized that the flexibility of the nasal probe mainsection, 52, and the two extensions, 54 and 56, are important inachieving the operational performance of the nasal probes of the presentinvention. One nasal probe has been constructed with TPE plastic and hada measured flexibility of 60 durometer units. Another nasal probe, alsomade with TPE plastic, was manufactured and had a measured flexibilityof 87 durometer units. In general, with regard to the plastic used fornasal probe main section, 52, and the two extensions, 54 and 56, thepreferred range for plastic flexibility is between about 60 and about 90durometer units.

Per the above, the distance between the probe extensions in relation tothe average dimensions of the septa of the target patient group is onefactor that provides for a suitable non-contiguous fit to obtain goodpulse oximetry data without undesirable patient discomfort and/or tissuedamage that results from a direct clipping of the probe extensions(arms) to the mucosal tissue of the nasal septum. Critical to thisapproach is not designing nor operating the nasal probe to applyingpressure to, attach to, or clamp on to, the nasal mucosal tissue wherethe pulse oximeter readings are being taken. It has been noted thatpractitioners in the field have expressed the need to, and havepracticed, applying pressure to a probe in order to stabilize the probe.While this may be required in finger or other extremity probes, this iscontraindicated when considering the delicate mucosal tissue that linesthe septum. Thus, in the present invention, the nasal probes, in theirsizing, material selection, and overall design, are such that theyperform to obtain pulse oximetry data by passing light through the nasalseptum, and the probes do this without applying pressure to the nasalseptum from both sides at the same time. That is, if any incidentalcontact is made to the actual nasal mucosal tissue from one extension,where either the light-generating or the light-detecting component ispositioned, the other such area (where the light-generating or thelight-detecting component is positioned) on the other extension is notthen in contact with the opposing side of the nasal septum mucosaltissue.

In summary, the nasal pulse oximeter probes of the present invention aredesigned, sized and constructed to direct light against sensitive andhighly vascularized mucosal tissue of the nasal septum without pressingagainst such tissue from both sides simultaneously, and to provide forlong-term use with minimal irritation or tissue necrosis.

Another aspect of certain embodiments of the present invention is thatthe light-generating and the light-detecting components do not protrudefrom the respective planes of the inner faces of their respectiveextensions. This is consistent with the teaching of the presentinvention that there is neither a need nor a desire to press into themucosal tissue of the nasal septum at the site adjacent to thesecomponents. In most embodiments, these components are positioned onrespective diode pads. These pads are placed within the respectiveextensions, and as a result, in certain embodiments, are recessed withinthe respective extensions.

Further as to the specific construction of the embodiment depicted inFIG. 2A-D, using the shrink-wrapping construction described above tocover the distal halves of the extensions 54 and 56, and dimensioningthe spacing between the extensions 54 and 56, so as to fit snuglyagainst the tissue of each side of the septum, these are found to fitwithout irritation, as from a rough or uneven surface. For example,without being limiting, when using heat sealing plastic as the covering,61, the thickness of this material, and any finish on the adjoiningedge, will affect the extent of a sensible ridge at the junction of thecovering, 61, and the molded outer shell, 69.

As to the specific area of the nasal septum that is preferred for use ofa nasal pulse oximeter probe such as the one depicted in FIGS. 2A-D, ithas been learned that the area of the nasal interior septum closest tothe face (e.g., the proximal area of the middle alar), is moreconsistently vascularized and thereby provides more consistent andreliable signals than the areas more distal, i.e., the interior septumcloser to the point of the nose. In particular, and more specifically, ahighly vascularized region of the septum known alternately asKiesselbach's plexus and Little's area, is a preferred target area fordetection of blood oxygen saturation levels by a nasal pulse oximeterprobe of the present invention. In the particular device shown in FIGS.2A-D, an angle of inflection, 70, is shown between plastic housing, 52,and the two extensions, 54 and 56. This angle properly is measured as aninterior (proximal) deviation from a straight line extended from theplastic housing, 52. In preferred embodiments, the angle of inflection,70, is between about 0 and about 33 degrees, in more preferredembodiments, the angle of inflection, 70, is between about 10 and about27 degrees, and in even more preferred embodiments, the angle ofinflection, 70, is between about 10 and about 20 degrees. In FIG. 8B,the angle, 70, is about 15 degrees. This angle has been found to providesuperior results in testing. Therefore, the angle shown in FIG. 2C,namely 60 degrees, is not a preferred angle of inflection.

Thus, in general, the two extensions, 54 and 56, are angled so that uponinsertion and proper placement into position in the nostrils, the LEDs62 and 64, located on extension 54, emit light directed through a regionthat includes the preferred, proximal area of the nasal septum. Mostpreferably, the LEDs 62 and 64, located on extension 54, directed lightexclusively through the highly vascularized region of the septum knownalternately as Kiesselbach's plexus and Little's area.

In addition, a stabilizer, 58, embodied in FIG. 1 as a flat plate flushwith and extending downward from the inside edge of the lower plane ofthe extensions 54 and 56 (before the extensions angle inward, see FIG.2C), is designed to press against the area between the upper lip andnose to hold the desired position of the probe, 50, and in particularthe LEDs 62 and 64, in relation to preferred, proximal area of the nasalseptum. The stabilizer, 58, alternately previously considered part of apreferred embodiment but not a necessary component, and, on latertesting, to irritate many users, is now considered to be valuable whenproperly oriented in relation to other components of the probe, 50.Additional means of stabilizing the probe, 50, such as elastic strapsfrom any part of the device that span the head of the patient, may beemployed with or separately from the stabilizer, 58. Thus, in preferredembodiments, no stabilizer, 58, is used, and the design of the device,as shown in other figures provided herein, with or without additionalstabilizing means, are adequate to stabilize the probe, 50, duringnormal wear.

As for the probe described above in FIG. 1, timed electrical impulsesfrom a pulse oximeter monitor system pass through two wires (not shown)in cables 61R and/or 61L to produce the light from LEDs 62 and 64. Atleast one photodetector, 66, is positioned on extension 56 to face andoppose LEDs 62 and 64 of extension 54. The photodetector 66, whichtypically is a light-sensing photodiode, detects changes in the lightemitted by the LEDs 62 and 64 as that light is differentially absorbedbetween and during pulses across the capillaries of the septum tissuebetween the two extensions, 54 and 56. In one embodiment, LED 62 emitslight around 650-670 nm, and LED 64 emits light around 880-940 nm. Theelectrical impulses are timed to be offset from one another. Thephotodetector, 66, detects the light passing through the septum of thenose, which is situated between extensions 54 and 56 when the probe 50is in use. As discussed above, loss of signal through vascularizedtissue such as the nasal septum is due both to background tissueabsorption and the absorption by the blood in the arteries, whichexpands during a pulse. The signals from photodetector 66 pass throughconductors (not shown) to the processor of the monitor system (notshown). The “signal” as used here, is meant to indicate the signal froma photodetector receiving light from one or more light sources of thepulse oximeter probe, which provides information about differentialabsorption of the light during different parts of the pulse. Thesesignals are to be distinguished in this disclosure from signals(electrical impulses) that are sent to the light sources to emit light,and from control signals that are sent, in certain embodiments, tocontrol a valve to supply more or less gas to a system.

Cables 61R and 61L preferably form a loop that may lie above the ears ofthe patient, and join to form a single cable (not shown). This singlecable preferably terminates in an electrical plug suited for insertioninto a matching socket in the pulse oximeter monitor system (not shown).In another preferred embodiment, the single cable terminates byconnecting to an adapter cable, which in turn connects to a socket inthe pulse oximeter monitor system (not shown). In a typical application,the signals from the light-sensing photodetector, 66, are ultimatelyreceived and processed by a general purpose computer or special purposecomputer of the monitor system (not shown). As used herein, the terms“monitor system” and “monitoring system,” may refer to the componentthat receives data signals from one or more probes, that is, thecomponent that comprises the general or specific-purpose computer thatanalyzes those data signals (i.e., the processor). This may be astand-alone unit (i.e., a console or, simply, pulse oximeter), or amodule that transmits data to a central system, such as a nurse'sstation. However, depending on the context, the terms “monitor system”and “monitoring system” also may encompass the entire assemblage ofcomponents, including such component and the one or more probes and theconductors (i.e., connecting wiring) that transmit data and controlsignals.

Also, it has been learned that a nasal probe, such as 50 in FIG. 2A-D,fits better and is found more comfortable by a patient when the cablesare glued to the main section, 52, of the body of the probe, 50, in thefollowing way. This method takes advantage of the natural bend in cable(and tubing) that comes from the rolled storage of such material on aspool. That is, wire, cable, tubing and the like that are rolled ontospools have a natural bend imparted thereby. It has been learned that ifthis bend is disregarded when assembling the cable sections to the mainsection, 52, then, for many nasal probes assembled with cables that goover the ears when in use, the probe, 50, and particularly itsextensions, 54 and 56, will have a tendency to rotate axially (inrelation to the cable crossing the lip laterally) outward or inward.This leads to discomfort, effort to readjust, and, at times, poor dataacquisition. To solve this problem, a section of cable long enough forboth sides of the probe is cut and placed unobstructed on a flatsurface. The natural bend from the spool configures this section in acurvilinear shape, typically nearly forming a circle. The two ends ofthis section of cable are inserted into the respective holes for thesein the molded flexible plastic that comprises the main section, 52, ofthe probe, 50 (an arrow in FIG. 2E points to a hole filled by a cable).The contiguous extensions 54 and 56 (typically part of the same moldedpiece as the main body, 52), are positioned flatly against the flatsurface, so the desired inward inflection (i.e., of 15 degrees) isdirected toward that flat surface, and preferably so the most inwardpoints of the extensions 54 and 56 (i.e., those that will be farthest inthe nose when in operational position) contact the flat surface. In thisposition, the cables are adhered or otherwise secured to the mainsection, 52, of the probe, 50. Typically, this is done by application ofa liquid adhesive to the holes where the cable ends enter the mainsection, 52 (i.e., see arrow in FIG. 2E). The cable then is cut toprovide two lengths, each one attached to one side of the main section,52.

When this method is practiced, due to the natural bend of the rolledcable (or tubing), the resultant cables 61R and 61L, when placed overthe ears, tend to gently orient the probe extensions, 52 and 54, axiallyinward, toward a desired vascularized part of the nasal septum. As such,comfortable nasal probes are produced, and the probes are more easilyadjusted to desired positions. Also, it has been observed that probesmade this way more generally maintain their desired positions, and thisis believed due to there being no undesirable countervailing force(i.e., the rotational force of some cables not assembled per thismethod) against whatever means are used to keep the probes in place.

Further with regard to embodiments of the nasal probe that provide anon-contiguous fit when inserted into a nose of a patient, use of suchprobes thusly to obtain photoplethysmographic data unexpectedly providessuperior results in comparison to prior art methods that simultaneouslypress (albeit lightly) both sides of the interior nasal septum, or, moreseverely, that grasp the nasal septum in such a way that there iscontact on both sides of the nasal septum at the same time with both thelight sources and the light detector. That is, an improved method forobtaining pulse oximetry and other photoplethysmographic data isdescribed as follows:

a) Through size estimation of the nasal septum to be used for datacollection, providing a nasal probe for insertion around the septum suchthat said probe non-contiguously fits said septum;

b) Inserting one extension of the nasal probe into each of the twonostrils of a patient, wherein one extension comprises at least twolight-generating components that emit light at at least two differentwavelength bands, and the other extension comprises at least onelight-detecting component that detects light transmitted from said atleast two light-generating components; and

c) Measuring, selectively, pulse oximetry and/or otherphotoplethysmographic properties of the blood flow in vascularizedinterior septum tissue positioned between said at least twolight-generating components and said at least one light-detectingcomponent;

d) Wherein said blood flow is not dampened by a simultaneous pressing ofsaid tissue from both sides at the point of measurement of said data.

Among other benefits, the data taken from the less dampened (compared tofinger probes) vascularized tissue of the interior nasal septum providesmore distinct signals having clearer information about cardiovascularparameters.

Further, it is noted that such method optionally additionally includeslocating a desired highly vascularized arterial plexus, such asKiesselbach's plexus, for the point of measurement, such as by usingperfusion index locating means, detection by lower LED powerrequirement, or other means known in the art.

Further with regard to embodiments of the lip/cheek probes, use of suchprobes to obtain photoplethysmographic data provides superior results.That is, an improved method for obtaining pulse oximetry and otherphotoplethysmographic data is described as follows:

a) Through size estimation of the thickness of the lip or cheek to beused for data collection, providing a lip/cheek probe dimensioned forinsertion around the lip or cheek so as to not squeeze the tissue, toavoid constriction of blood vessels therein (such constrictionmeasurable by comparative data with probes having different distancesbetween the pads);

b) Placing the distal arm of said probe into the mouth to a desiredposition; and

c) Measuring, selectively, pulse oximetry and/or otherphotoplethysmographic properties of the blood flow in vascularizedtissue positioned between said at least two light-generating componentsand said at least one light-detecting component.

In particular, it is noted that the probe, after initial placement to adesired position, is adjusted to a more desired position providing agood signal. This is done such as by comparing signals from thedifferent possible positions. Thereafter the cable leading from theprobe (which typically is placed over the top of one ear) is taped tothe outside cheek to stabilize and maintain this selected position. Ithas been found that a desired positioning often is with the bridgingsection, 2, of the probe positioned in or near one corner of the mouth,with the cable leading over one ear. In such positioning thelight-generating and the light-detecting components are positionedaround an area of the cheek a distance from the corner of the mouth. Itis noted that the lip/cheek probe has been found to functionconsistently, without interference from movement of the mouth, inpatients who are under anesthesia or on sedating medications. This isnot meant to be limiting, as other uses are considered appropriate,taking into account, as needed, a possible effect of mouth movement andresultant interference of signals during periods of such movement.

In a variation of the nasal probe, such as is exemplified in oneembodiment in FIG. 2A-D, oxygen is delivered with the same device thatalso measures trans-septum arterial oxygen saturation (see FIG. 8A, B).In another variation, the pulse oximeter sensor is independent of anoxygen cannula, and is a single-use unit. In yet another variation, thepulse oximeter sensor is independent of an oxygen cannula, and isre-usable and readily cleanable with appropriate antiseptic cleaningagents. Other variations within the scope of the invention described andpictured can be developed by those of ordinary skill in the art.

FIG. 3 illustrates a third pulse oximeter probe, 100, of the invention,that is configured for placement on the tongue of a patient formeasurement across the vascularized tissue of the tongue. The probe,100, has two substantially flat opposing arms, 104 and 106. A housingcover, 105, is joined with a housing base, 107, to form each of the twoarms, 104 and 106. At one end of each of the two arms, 104 and 106, arefinger pads, 108 and 110, which in the embodiment shown in FIG. 3 are onthe housing covers, 105, and possess ridges, 111, to improve the grip.

The arms, 104 and 106, are tensioned to close against one another by aspring (not shown) which has a fulcrum at or near an axle, 109, thathingedly connects the two arms, 104 and 106, near one end. At or nearthe other end is an LED pad, 112, on one arm, 104. Within this pad, 112,are two light generating sources, here shown as LEDs 114 and 115.Opposite this housing, 112, on arm 106, is a photodetector pad, 116.Within this pad, 116, is at least one photodetector, 118. Electricalwire conductors (not shown) connect the LEDs, 114 and 115, and thephotodetector, 118, to a pulse oximeter monitor system (not shown), viaa cable, 120, passing from one end of the arm, 104. The inner surfacesof the arms, 104 and 106, in some variations of this probe are knobby orotherwise textured, especially around the LED pad, 112, and thephotodetector pad, 116. This texturing is designed to better maintain astable position of the probe, 100, on the tongue without use ofexcessive pressure of the spring.

The photodetector 118, which typically is a light-sensing photodiode,detects changes in the light emitted by the LEDs 114 and 115 as thatlight is differentially absorbed between and during pulses across thecapillaries of the tongue tissue between the two arms, 104 and 106. Inone embodiment, LED 114 emits light around 650-670 nm, and LED 115 emitslight around 880-940 nm. The electrical impulses are timed to be offsetfrom one another. The photodetector, 118, detects the light passingthrough the tongue which is situated between the first housing, 112, andthe second housing, 116 of arms 104 and 106 when the probe 100 is inuse. As discussed above, loss of signal through vascularized tissue suchas the tongue is due both to background tissue absorption and theabsorption by the blood in the arteries, which expands during a pulse.The signals from photodetector 118 pass through conductors (not shown)housed in cable 120 to the processor of the monitor system (not shown).Cable 120 preferably terminates in an electrical plug suited forinsertion into a matching socket in the pulse oximeter monitor system(not shown). In another preferred embodiment, cable 120 terminates byconnecting to an adapter cable, which in turn connects to a socket inthe pulse oximeter monitor system (not shown). In a typical application,the signals from the light-sensing photodetector, 118, are ultimatelyreceived and processed by a general purpose computer or special purposecomputer of the monitor system (not shown).

There are numerous means for hingedly joining the first arm and thesecond arm other than by an axle passing through the extensions of eacharm (e.g., by axle 109). Other means include hinges of various materialsand designs as known in the art, co-fabrication of the arms with athinner section of flexible plastic between the two arms at one end, andpins, screws, and other fasteners as are known to those skilled in theart.

Similarly, means for tensioning the first arm and the second arm, so asto properly maintain tension on a section of the tongue of a patient,can be effectuated by means other than the spring described above.Separate elastic bands may be attached or may surround the arms, such asby attaching to protrusions spaced appropriately along the arms. Also,the natural flexibility and resilience of a co-fabricated structurecomprising both arms connected by a section of resilient plastic canprovide both the means for hinging and the means for tensioning. Suchfabrications may be deemed suitable for disposable units.

It is noted that for this and other probes disclosed herein, a singlesource generating at least two different light frequencies may beutilized instead of LEDs. Alternately, more than two LEDs may be used,such as to generate light at more than two frequency bands, for instanceto increase accuracy and/or detect other forms of hemoglobin. Also,light receiving sensors, or photodetectors, other than photodiodes maybe used, and more than one such sensor may be used in a single probe.

The pulse oximeter probes, such as 10, 50, and 100 as depicted and asused with the monitoring systems in the present invention, takemeasurements by transillumination as opposed to reflectance. This is thepreferred configuration. However, for any of these probes, both thelight-generating devices, and the photodetector devices, can beconfigured adjacent to one another, on one arm or extension, to measurereflectance of the tissue on the interior of the mouth (e.g., thecheek), the lip, the nasal septum, or the tongue.

FIG. 4 depicts another general configuration of an oximeter probe of thepresent invention. This probe 10 can be dimensioned and configured to beexpandable and tensioned to close by a spring, 18. Near the distal,operative end of one substantially flattened side, 20, is an LED array,16, and opposing it near the distal, operative end of the opposingsubstantially flattened side, 21, is a light detecting sensor,preferably a photodiode, 15. A cable, 4, connects the LED array, 16, andlight detecting sensor to a pulse oximeter monitor system (shown in themagnified end view)). This pulse oximetry probe can be used to measurepulse-based differences in light absorbence across vascularized tissueof a patient in a number of locations, including but not limited to thecheek, the lip, the nasal alars (alar nari), the nasal septum, fingers,and toes.

By “substantially flattened” is meant that the height of the structureof a side is small relative to the greater of the length or width ofthat side. Preferably the ratio of the height to the greater of thelength or width of a “substantially flattened” side is between about0.2:1 and 0.001:1, more preferably this ratio is between about 0.02:1and 0.005:1, and yet more preferably this ratio is between about 0.01:1and 0.005:1. For greater applicability to typical physical requirementsin use, each side also is substantially longer than wide. By“substantially longer than wide” is meant that the width of thestructure of a side is small relative to the length of that side.Preferably the ratio of the width to the length of a side described as“substantially longer than wide” is between about 0.7:1 and 0.02:1, morepreferably this ratio is between about 0.025:1 and 0.05:1, and yet morepreferably this ratio is between about 0.025:1 and 0.1:1. At a minimum,with regard to nasal pulse oximeter probes of the present invention, thekey functional attributes of extensions that are substantially flattenedand/or substantially wide, as used herein, is that the width of suchextensions is sufficient to house the components (i.e., circuit boardsbearing LEDs and photodetectors, or the LEDs and photodetectorsthemselves), and the length of such extension is sufficiently long toprovide the LEDs and photodetectors on opposite sides of a desiredregion of vascularized tissue. The same functional logic applies toother sensors disclosed and claimed herein.

Also, it is noted that in place of the spring, 18, any hinging means asknown in the art can be used. Such hinging means may include a raisedsection along or separate from the sides, such that a fixed space iscreated at the point of the hinging means. This would obviate the needfor a bend in the sides at the spring, 18, as shown in FIG. 4 (which isrequired in FIG. 4 to lever open the operative ends). Thesesubstantially flattened probes are configured such that the inner facesof both sides substantially oppose each other and, based on the spacingand configuration of the hinging means, are sufficiently separable towiden to encompass a desired tissue to be monitored for blood oxygensaturation between the light emitting structure and the light detectingstructure at the operative end. It is noted that these structure mayeach be enclosed in a pad, or may not be so enclosed. As for otherprobes disclosed herein, a monitoring system connected to the probemodulates light signal production and receives signals of light detectedby at least one light-detecting structure positioned at the operativeend of one of the sides, such as 20 or 21 in FIG. 4. Typically a pulseoximeter or photoplethysmography monitoring system console includes, orcan be connected to, a video monitor that provides graphical andnumerical output from the signals received from the photodetector, whichare algorithmically processed by a special-purpose (or general-purpose)computing component in the monitoring system console.

Also, the above substantially flattened sides with hinging means may beproduced without light-emitting and light-detecting structures, andsleeves, such as described below, bearing such structures, would then beslipped over the sides to yield an operable oximeter probe. Forinstance, as shown in FIGS. 4 and 6, a probe 10 with a flat surface 20is suitable for to receive a flexible sleeve, 22, that bears an LEDarray, 16, and light detecting sensor, preferably a photodiode, 15. Thisslips over the flat-surfaced structure, as shown about halfway on inFIG. 6. As for the probe in FIG. 4, a cable, 4, connects the LED array,16, and light detecting sensor to a pulse oximeter monitor system (notshown).

In operation, the devices depicted in FIGS. 4-6 are placed around afinger, earlobe, or other extremity in order to obtain data.

Thus, another aspect of the present invention is a disposable sleevethat fits over any of the pulse oximeter probes disclosed and claimedherein, and over conventional probes. A sleeve is constructed of aflexible material, and is relatively thin, in the general range of 0.005to 0.050 inches thick, more preferably in the range of 0.010 to 0.025inches thick, and most preferably in the range of 0.010 to 0.015 inchesthick. The sleeve is manufactured to slide over the major structuralfeatures of the probe to provide a barrier to reduce the chance ofcontamination from one patient to a second patient using the same probe.An example of such sleeve is shown in FIG. 5, and its implementationover a probe is shown in FIG. 6. In this case the sleeve is constructedto include the light generating and the light sensing features, andassociated conductors. However, in other embodiments of the sleeve, suchfeatures are on the major structural features, whether frames, arms,etc., and the sleeve slides over such features, and at least in theareas of such light producing and light sensing features the sleeve ishighly transparent to the critical wavelengths used by the pulseoximeter. The sleeves cover both arms, or extensions, of probes havingtwo distinct arms. Preferably a continuously integral section of thesleeve joins the sleeve sections that cover both arms or extensions ofthe probe, in order to, inter alia, protect the intervening parts of theprobe. For a probe such as the probe of FIG. 1, the sleeve is configuredto the shape of the probe and slides over starting at the end, 4, of thearm, 3, and covers up to, and preferably including, the boot, 8.

In some sleeve embodiments, a stretchable aspect of one or more parts,or of the entire sleeve, stretches over a protuberance or otherprominence at one or more parts of the major structural features overwhich the sleeve is sliding, and improves the fit of the sleeve. Thisalso better assures that the sleeve does not slide off the probe duringnormal uses. Alternate means to secure the sleeve onto the probe such asare known to those of skill in the art may be used. The sleevesthemselves can be disposable; however, the sleeves also can be made ofeasily sterilizable materials and be sterilized between uses.

The probes and the sleeve covers of the present invention are suppliedas clean or as sterile, depending on the needs of the end user and thebudgetary constraints of the end user. Clean but not sterile probes andsleeves will be less expensive, and may be suitable for manyapplications. Where there is an elevated risk of major harm from aninfection, for instance in immunocompromised patients undergoingtransplants with immunosuppressive drugs or undergoing chemotherapy,sterile probes would be more appropriate than merely clean probes. Manyconfigurations of the probes are cleanable using alcohol and/ordetergent/disinfectant solutions, and other configurations aredisposable.

All of the above disclosed probes operate in a typical manner of a pulseoximeter, as described herein and in articles and patents cited andincorporated by reference. Each LED emits its specific frequencyhundreds of times per second, and the absorption (or transmittance)readings by a sensor, such as a photodiode, are transmitted to acomputer. There a software system performs averaging (optionallydeleting outliers), and by differences in wavelengths' absorption ortransmittance at the pulse peaks, determines arterial oxygen saturation.In a standard two-LED system, this is done by an algorithm thatcalculates the ratio of the peak absorbence at 650-670 nm divided by thebase absorbence at this wavelength range, and compares this ratio to thepeak absorbence at 880-940 nm to the base absorbence at the 880-940 nmrange. The base absorbence reflects the non-pulse background absorbenceby tissues other than the artery at maximum width during the pulse. Thiscalculation provides an estimate of arterial oxygen saturation. A graphof the pulse surge, or shape, over time, also can be obtained.

All of the above-disclosed probes are expected to have significant usein the intensive care units, operating rooms, post-surgery recoveryrooms, and in ambulance related situations where a patient in need ofmonitoring has few suitable monitoring sites. The size and shape of eachprobe will depend on whether the patient is an adult or child.

When two or more probes are used together, data from multiple probes isprocessed to provide continuous and simultaneous cross-site comparisonsof the arterial blood oxygen saturation status at and comparisonsbetween two or more tissue sites (and, as desired, blood pressureestimates based on transit time differences and/or other relatedparameters). The monitoring system receiving these signals includes atleast one program containing computer software (not shown) comprisinginstructions which causes the computer processor to receive andcalculate various oxygen saturation values. Optionally, the monitoringsystem may receive signals from separate probes or sensors to assessblood pressure values, which optionally may be compared (eithersimultaneously or separately) with blood pressure estimates based onsignals received from each of the probes determining arterial bloodoxygen saturation and vascular perfusion/resistance of a patient.Depending upon the software used, and the addition of separate bloodpressure probes or sensors, the monitor may be used as a dual pulseoximeter, a saturation difference monitor, a transit time monitor, aperiodic blood pressure monitor, or a noninvasive continuous bloodpressure monitor. Specific examples are provided below that demonstratea non-exclusive range of applications for the monitoring system whichcompares signals from a central source site (CSS) with signals from atleast one advantageously positioned peripheral site (PS), as those termsare defined herein.

FIG. 7 depicts the steps of a basic method using the monitor system thatincludes one probe positioned in a CSS, and one probe in a PS. A firstpulse oximeter probe is removably affixed to a CSS in the head of thepatient. This is most preferably any of the specially configured probes,or could be a conventional probe. A second pulse oximeter probe isremovably affixed to a PS such as a finger or a toe. This can be any ofthe specially configured probes, or a conventional probe. The monitoringsystem is started, the LEDs or other light generating sources in theprobes emit designated light at designated frequencies andperiodicities, and signals from the CSS and from the PS are measured andtransmitted to the monitoring system computer. Here, adjacent signals ofthe same type (wavelength and probe) are averaged to obtain astatistically reliable average. As appropriate based on the softwareprogram, certain outliers as may be caused by movement of the patient,light contamination from an outside source, etc., are eliminated fromconsideration. The averaging is repeated and the averaged values arecompared based on the time sequencing of the respective averages. Thatis, average values from a specific time from the CSS probe are comparedto average values from the same time span from the PS probe. Thesoftware calculates arterial blood oxygen saturation percentages basedon the differential absorption of the different species of hemoglobin,and percent oxygen saturation at the CSS and the PS are compared. Basedon criteria input into the monitoring system and reflected in thesoftware's calculations, the presence or absence of impaired peripheralperfusion are shown as an output reading of the monitoring system.Alternatively, if impaired perfusion has already been established, thetracking of time-based changes in the saturation differences between theCSS and the PS are read out or charted.

The method shown in FIG. 7 is conducted with an apparatus having thestated functional capabilities. Also, an oximeter monitoring system hasthe basic physical components that perform the required centralizedfunctions, and which is attached to at least two oximeter probes toperform the above-described method.

Further, a variation of the method of FIG. 7 is to have an additional PSprobe, and compare not only the first PS probe to the CSS probe, but toalso compare the first and second PS probes' signals to one another.This can, for instance, demonstrate impaired peripheral perfusion in onebody area, but not in another body area or extremity.

The apparatuses, methods and systems of the present invention can beapplied to both humans and animals, i.e., to living vertebrateorganisms. Its application in human medicine (adult & pediatrics) wouldsignificantly improve the estimation of vascular perfusion or resistanceby pulse oximetry; however, veterinary medicine also would greatlybenefit from its use. This superior monitoring system would utilize atleast two pulse oximeter probes, one of which is designed for use with ahighly perfused central tissue, such as a lip, tongue, nares, cheek; andthe other probe is designed for use to less perfused areas such asperipheral tissues, or any combination thereof.

The following specific examples are meant to be demonstrative, but notlimiting, of the possible applications of the present invention.

Example 1

Data from a small number of volunteer subjects was obtained. This dataprovided preliminary support for the hypothesis that differences in CSSand PS estimates of arterial blood oxygen saturation levels can providediagnostic information about the status of peripheral blood circulation.These data are summarized below.

All sets of data were taken three times, except that data for subjects 1and 9 were only taken two times (duplicate data sets). Subjects 1-3 hadno history of chronic obstructive pulmonary disease or other conditionsthat would be expected to cause lowered peripheral circulation. Exceptfor one reading of 93% for subject 1, all estimates of arterial oxygensaturation were 95% or higher, and the PS (a finger, using a standardcommercial probe) readings were within two percentage points of eitherCSS sites (lip and cheek). For the data set in which subject 1's cheekprobe reading was 93%, the lip reading was 98% and the finger readingwas 96%. Overall, the data of subjects 1-3 suggest that in a healthysubject the CSS and PS readings taken at or near the same time will berelatively close, within about 5 percentage points or less, and all ofthe readings will be high.

Subject 4 had average readings at the PS finger site of 89%, and at theCSS cheek site, 88.7%, so these sites has essentially identicalestimates. No signal was recorded at the lip CSS. Although there was nodifference between the CSS cheek and the PS readings, the oxygenestimate was low and indicated a generalized problem.

Subject 5 had a PS average of 85%; the lip CSS average was 88.3%, andthe cheek CSS average was 91.3%. The absolute levels are low, and thedifference between CSS and PS values ranges from about 3 for the lip toabout 6 for the cheek. This appears to suggest a peripheral circulationproblem, and the low absolute levels indicate a generalized problem withoxygenation. This subject was known to have COPD.

Subjects 6-8 were known to have COPD. The average values for finger, lipand cheek were 85, 90, and 89, respectively for Subject 6. The 4-5% lesspercent saturation for the peripheral site supports the presenthypothesis. Subject 7's finger data varied between 77-80% during thereadings, and is considered unreliable. One of subject 8's data pointsfor the finger was 79%, whereas the other two were 85%. This suggeststhat the 79% reading is erroneous. Disregarding this data point, Subject8 had 85%, 87.3%, and 85.6% averages for the finger, lip and cheeksites, respectively. Here, all readings are fairly close, and theabsolute values are alarmingly low. The data from this subject do notsupport the hypothesis; however the circulation for this subject may notbe impaired peripherally. Further investigation can resolve this andother points.

Regarding the latter, subject 11's data was anomalous in that the fingersite averaged 93.3%, whereas the lip and cheek sites averaged 90.7% and86.7%, respectively. The reason for this is unknown; the data could bespurious or could indicate unusual circulation in a small percentage ofthe population. Individual differences in circulatory systems (based inpart on genetics, and in part on non-genetically based embryologicaldevelopment, and on physical conditioning) may form the basis for suchanomalies in a percentage of the population. Highly variable andincomplete data for Subjects 9 and 10 were considered to render thevalue of their data questionable, and those data were not analyzed.

Thus, this preliminary data provided some indication of differencesbetween CSS and PS and differences between normal andcirculation-compromised subjects. The data also supported the need toinvestigate broader populations with known circulatory conditions todevelop more predictive guidelines for the probe data differences. Evenwith the limited data of this example, it is apparent that thecomparison of CSS and PS sites can provide a useful assessment of thestate of the circulatory system even where there is no major difference,and there is not a disease state presenting itself. That is, suchresults of roughly equivalent CSS and PS data at a high oxygensaturation level would support a conclusion that the peripheralcirculation is not impaired.

Example 2

An elderly patient with relatively advanced diabetes comes in formonitoring of the status of perfusion in the right leg, which isdiagnosed with severe atherosclerosis and related impaired vascularperfusion. A monitor of the present invention is utilized, with one CSSprobe measuring signals across the nasal septum, and a PS probe on thelarge toe of the right foot. A new medication is started, and ongoingweekly data from the monitor tracks the changes in perfusion in theright leg by comparing oxygen saturation values of the CSS probe withthe values of the PS probe. Such data indicates the degree ofeffectiveness of the new medication.

Example 3

A critically burned patient is brought into an emergency room. As vitalsigns and assessment is taking place, a pulse oximeter probe as shown inFIG. 1 is placed into the patient's mouth to read cheek tissue as acentral site source, and a pulse oximeter probe as shown in FIG. 4 isplaced at each of the patient's large toes. Within less than one minute,the monitor of the present invention indicates below normal bloodperfusion in the right leg, based on the signals from the probe placedon the right toe, compared to the central source site and the left toeprobe. A probe is placed on a right finger, and this provides comparabledata to the left toe. The attending physician is able to surmise that aninjury or disease condition is adversely affecting perfusion in theright leg, orders more detailed testing, and increases the percentoxygen on the respirator to counter the low oxygen in the affected leg.The monitoring system tracks changes in the oxygen saturation values ofblood in the right toe as this initial treatment has an effect.

Example 4

A patient suspected of having Chronic Pulmonary Obstructive Disease isadmitted to an emergency room with breathing difficulties. The patientalso reports pain in both legs after involved in a minor trafficaccident, which is the immediate cause of admission. Minor bruising isapparent on the front of the left leg. Along with other tests andmonitoring, a pulse oximeter monitor of the present invention isutilized, with on CSS probe on the nares of the nose, and a PS probe onthe large toe of each of both feet. Alarmingly, the CSS probe estimatesthat the arterial oxygen saturation at the CSS site is below about 85percent, indicating hypoxia. The pulse oximeter monitor in both PS sitesestimates even lower oxygen saturation, by about 5 percent, compared tothe CSS site. There is no response to bronchodilator therapy, and thechest x-ray shows moderate fibrosis, and no attenuated vessels orhyperinflation. The initial diagnosis, aided by the pulse oximetry data,is bronchial COPD. Oxygen therapy is provided, and the pulse oximetrydata is utilized to monitor increases in blood oxygen saturation both atthe CSS and PS sites.

It is noted that the following paragraphs, through and including Example5, describe embodiments of the present invention which combine,preferably integrally, a pulse oximeter probe with a nasal cannulathrough which is delivered a supply of oxygen or oxygen-rich air. Insome of these embodiments, the combined pulse oximeter sensor/nasalcannula with oximeter is used to monitor and provide informationregarding the oxygen saturation status, using data obtained from thesensor through the tissue of the nasal septum, to the user of thedevice, to caretakers of that user, and/or to a remote station thatutilizes the information. For instance, the user can view current and/orhistorical trend data and manually adjust the flow rate of the oxygen oroxygen-rich air accordingly. Alternately, a user of said combined pulseoximeter sensor/nasal cannula with oximeter, in advance of a period ofexpected increased exertion, may increase the flow rate of his/herauxiliary oxygen supply. Then, during such exertion, such user refers tothe oximeter data output and further adjusts the flow rate as needed toattain or remain within a desired range of blood oxygen saturation asindicated by the data output from the oximeter.

In other embodiments, the combined pulse oximeter sensor/nasal cannulais used in further combination with a central processing unit that sendssignals to automatically adjust the flow rate of the oxygen oroxygen-rich air to the use. For instance, and not to be limiting, duringmore strenuous exertion, arterial blood oxygen saturation of a personneeding oxygen supplementation therapy is expected to declineappreciably. In such circumstance, this drop in oxygen saturation isdetected by the pulse oximeter probe, the trend data is analyzed by aprogram in the central processing unit, and a signal is sent to avalving mechanism that results in a greater oxygen flow directed throughthe user's cannula. A feedback loop, the data from the nasal pulseoximeter going to the central processing unit monitoring system,subsequently decreases the flow when the data indicates arterial bloodoxygen saturation has exceeded a designated percentage. By such feedbackloop approach, the oxygen delivered via the nasal cannula is betteroptimized for actual physical exertion and/or changing metabolicrequirements.

In other embodiments, which are preferred in certain applications, theuse of data from the nasal pulse oximeter to regulate oxygen flow to thenasal cannula is combined with other approaches to conserve oxygen,which include, but are not limited to:

1. detection of the inhalation phase of the respiration cycle to providethe oxygen (or oxygen-enriched gas) only during inhalation (or a keysegment of the inhalation, i.e., the initial ⅔ of the inhalation);

2. providing oxygen every other breath; and

3. providing greater volume and/or flow rate at key part(s) ofinhalation cycle (i.e., increased “shot size”).

In yet other embodiments, which are preferred in certain applications,the data from the nasal pulse oximeter is combined with data collectionof other parameters. For instance, in studying sleep disorders, a numberof parameters are measured, for instance, pattern or dynamics ofrespiration (flow rate, inhale/exhale over time cycles), pulse rate,etc. In embodiments of the present invention, the use of the combinednasal pulse oximeter probe is combined with other monitoring sensors atthe nose that detect, for instance, but not to be limiting, air flow andair pressure, such as during sleep, to analyze an individual's sleepdisorder, such as sleep apnea.

Thus, when blood saturation information from the so-combined pulseoximeter probe is processed over time, and when trends are detected inthe oximeter probe data processor that indicate a need for more or forless oxygen to the patient, based on, respectively, lower or higherblood oxygen saturation readings than a desired range, one or moreoutcomes result. As noted above, one outcome is to automatically adjustthe supply of oxygen or oxygen-rich air to provide a needed increase (ifreadings were trending lower) or a decrease (if readings were trendinghigher, above a desired range, and conservation of the supply weredesired) of that supply. Another outcome is to provide an alarm signal(audible, flashing, etc.) locally, for recognition by the patient or anearby attendant. Yet another possible outcome is to provide a remotealarm, such as by cellular telephone transmission, to a physician'soffice, an ambulance service or hospital, etc.

Further, it is noted that there exist in presently used devices otherapproaches to conserving the supply of oxygen or oxygen-rich air. Onecommonly used approach, often referred to a the “pulse-dose” system,delivers oxygen to the patient by detecting the patient's inspiratoryeffort and providing gas flow during the initial portion of inspiration.This method is reported to reduce the amount of oxygen needed by 50 to85% (compared to continuous flow) and significantly reduces the cost,the supplies needed, and the limitations on mobility caused by a limitedoxygen supply.

For example, as the patient initiates a breath, the cannula tip sensesthe flow, a solenoid valve opens, and a burst of oxygen is rapidlydelivered to the patient. The size of the burst or flow varies amongdifferent manufacturers. Commonly, the pulsed-dose system takes theplace of a flow meter during oxygen therapy and is attached to a 50 PSIGgas source. In most devices the patient or operator can choose the gasflow rate and the mode of operation (either pulse or continuous flow).Typically, a battery-powered fluidic valve is attached to a gaseous orliquid oxygen supply to operate the system.

In addition, other approaches are used to further reduce oxygen usagewhen using the pulse-demand system. One such approach is to reduce thedose of oxygen delivered to the patient during each pulsation. Anotherapproach, in combination or independently of the last one, is to delivera burst only on the second or third breath instead of every breath. Inaddition, the size of the oxygen pulse dose will change with the flowsetting with increases in flow delivering larger doses of oxygen andvice versa.

It is noted that potential problems encountered when using thepulse-demand system include: no oxygen flow from the device; anddecreased oxygen saturations in the patient. If no oxygen flow isdetected, then possible causes include a depletion of the gas supply, anobstruction or disconnection of the connecting tubing, or, criticallyfor a pulse-demand system, an inability of the device to detect thepatient's effort to breath. If the device cannot detect the patient'sinspiratory effort, the sensitivity will need to be increased or thenasal cannula will need to be repositioned in the nares.

A decrease in the patient's oxygen saturation should always be a causefor alarm and may indicate a change in the patient's medical status,tachypnea, or a failure in the device. In any case, a backup systemshould be available in order to verify whether the problem is with thedevice or with the patient.

Thus, although in common use, the limitations of many pulse-dose systemsare: relatively high cost of the system; technical problems may beassociated with such a complicated device (including disconnections,improper placement of the device, and a possible device failure); lackof accommodation for an increased need during exercise, stress, illness,etc. and variable operation of the device if not properly set up.

Variations on the pulse-dose system include delivering oxygen to thepatient at the leading edge of inspiration. This allows oxygen to besupplied exactly when needed. Thus, when the patient inhales, arelatively higher quantity of oxygen is delivered for travel deep intothe lungs, increasing the probability of greater utilization and uptakein the red blood cells in the person's bloodstream. Other variations onthe pulse-dose system are known in the art.

The present invention is used independently of the pulse-dose system,or, alternatively, in conjunction with such system, to conserve thesupply of oxygen or oxygen-rich gas, and to better adjust the supply tothe actual demands of the patient/user as that person's physicalactivities and demands vary over time. In particularly preferredembodiments, the pulse oximeter probe that is in combination with anoutlet (e.g., the end of a cannula) of the supply of oxygen oroxygen-rich gas is fashioned to be integral with, or securely fastenedto, that outlet. This provides greater surety of signals and properinsertion of the outlet. For instance, when the pulse oximeter probe isintegral with the nasal cannula, if the probe and device areaccidentally moved from their proper location (e.g., entrance of nose,or mouth), then the oximeter readings (including pulse) will deviatesharply from normal. In such instance an alarm can be quickly soundedand the problem rapidly corrected. Thus, this provides a distinctadvantage in comparison to peripheral probes, such as finger or toeprobes.

Another aspect of the present invention is adding as an additionalsensor a capnography sensor (such as an infrared sensor) to estimate theconcentration of carbon dioxide in the exhaled breath. This may beuseful to detect more rapidly than pulse oximetry the failure ofventilation means (such as the wrong gas being provided to the patent),or carbon dioxide poisoning. Regarding the latter, the article entitled“Management of carbon monoxide poisoning using oxygen therapy” by T W LMak, C W Kam, J P S Lai and C M C Tang, in Hong Kong Medicine Journal,Vol. 6, No. 1, March 2000 is instructive.

Also, as to the detection of a failure of ventilation means, when thepresent invention's combined nasal pulse oximeter sensor/cannula isattached to a pulse oximeter that is programmed to distinguish normalfrom abnormal pulse ranges, and when the combined nasal pulse oximetersensor/cannula falls away from the user's nose (e.g., by accident duringsleep or sedation, etc.), an alarm can be quickly provided based on thelack of pulse in the proper range. In this way the combined nasal pulseoximeter sensor/cannula more rapidly detects a loss of supplementaloxygen more rapidly than typical capnography detectors as to this reasonfor loss of ventilation.

Thus, the following examples are to be understood to be usableindependently or in combination with the above described otherapproaches to conserving the supply of oxygen or oxygen-rich gas, and/orwith other approaches known in the art but not described above,including those referred to in references cited herein.

Example 5

FIG. 8 depicts one embodiment of a nasal oximeter probe, such asdepicted in FIGS. 2A-D, in which the oximeter function and hardware arecombined and integral with a cannula to supply oxygen (or oxygen-richair or other gas mixture) to via the nostrils of the patient. Thedevice, 150, shown in FIGS. 8A, B is but one specific embodiment of arange of designs and combinations that include a pulse oximeter probe incombination with an outlet for oxygen or oxygen-rich gas to a person inneed thereof. For instance, while in the present example a cannula(defined as “a tube for insertion into body cavities and ducts, as fordrainage”) is used within the nasal oximeter probe to conductoxygen-rich air or other gas mixture into the nostrils of a patient, anyof a range of different conduits can serve this purpose. As one example,not meant to be limiting, a passage can be formed by molding suchpassages within the structure of the nasal oximeter. Such passagesthemselves can serve to conduct oxygen-rich air or other gas mixtureinto the nostrils of a patient. Alternately, these passages can be sizedand configured to allow cannula tubing to be inserted through suchpassages, to provide for relatively easy assembly with standard cannulatubing which is common with standard regulators and tanks Thus, the term“passage” is taken to mean any physical structure, now or later known tothose of skill in the art, that provides for the physical containment ofa gas that is being directed through such structure. Common forms ofpassages include cannula tubing, standard plastic tubing, and thecontinuous voids in a molded nasal pulse oximeter through which a gasmay pass without loss from seams, etc. in the voids.

FIG. 8A is a front view, and FIG. 8B is a side view of the combined, orintegral, nasal probe/cannula, 150. From a resilient plastic housing,here depicted as comprised of a main section, 152, protrude twoextensions, 154 and 156, that are sized to enter the nares of the nose.Preferably, the lateral cross-sectional surface area of each of theseextensions, 154 and 156, is not greater than 50 percent of the openingcross-section area of a nares at its widest opening, more preferably thedevice's inserted cross-sectional surface area is not greater than 35percent of such opening area of a nares, and even more preferably, thedevice's inserted cross-sectional surface area is between about 20 andabout 35 percent of such opening area of a nares. At the end of theseextensions, 154 and 156, which preferably are of molded plastic andintegral with the major portion, the plastic housing, 152, are insertedtwo circuit boards, 163, one containing two light-emitting diodes, 162and 164 (shown here on extension 156) and the other containing aphotodetector, 166 (shown here on extension 154).

As discussed for FIGS. 2A-G, in certain embodiments, the two extensions,154 and 156, are spaced apart from one another so as to fit snuglyagainst the tissue of each side of the septum to avoid interference fromambient lighting. Moreover, in certain embodiments as described above,the two extensions, 154 and 156 are constructed and spaced apart so asto fit non-contiguously with the mucosal cell lining of the interiorseptum walls.

Also, as discussed for FIGS. 2A-G, it is noted that clear plasticcovers, 161, are placed over the molded plastic frame, 169, that formsthe extensions 154 and 156 in FIGS. 8A-B. These plastic covers typicallyare heat-sealed over the LEDs 162 and 164 and photodetector 166. Invarious embodiments, the sides, 165, of the clear plastic covers, 161,that are facing or contacting the nasal septum (not shown) are alignedwith the inside faces, 167, of the extensions 154 and 156, so as to fit,respectively, near or against the tissue of each side of the septum,without irritation, as from a rough or uneven surface. As noted in moredetail elsewhere, the covers, 161, preferably have inner faces co-planarwith the inner faces of the two extensions, 154 and 156. This is toensure a comfortable fit, good data since ambient light is lessened, andno necrosis of the tissue being contacted. In all such embodiments, itis preferred that the two extensions, 154 and 156, deflect from theseptum wall due to flexibility of the structures themselves, 154 and156. This is particularly helpful when a patient has an interior septumwall wider than the spacing between the inner sides, 165 (so that thereis substantial contacting), when a patient has septum wallirregularities (i.e., a deviated septum wall), or when a patient has acolumella substantially wider than the inner faces, 167. Also, dependingon relative sizing of nasal probe to a septum, embodiments as describedherein are designed and sized to fit providing a space between the innersides, 165, and the mucosal lining of the interior septum. Otherembodiments are designed and sized to provide such space, and also to beseparated from, or apply less pressure against, the columella.

Further as to the plastic covers, 161, one is fitted over each of thestructures, 163, that contain the LEDs 162 and 164, located on extension156, and the photodetector 166, located on extension 154. The plasticcovers, 161, preferably do not interfere with light transmission. Apartfrom heat-shrink sealing, other means of attaching the plastic covers,161, to the extensions 154 and 156, include, but are not limited to,sonic welding, spot gluing, hot gluing, press fitting, and other suchmethods of attachment, as are employed in the art, that are used toattach components of a medical device for entry into an orifice of aliving subject. In general, the combined nasal pulse oximeterprobe/cannula devices of the present invention are designed to bedisposable, due to problems associated with cleaning between uses.However, it is within the scope of the invention that appropriateplastics, components and construction are employed so as to allow anappropriate level of sterilization of such devices between uses.

As for the nasal pulse oximeter probe depicted in FIGS. 2A-D, twoextensions, 154 and 156, extend from a main section, 152, of a resilienthousing, typically of plastic, that positions and spaces the extensions154 and 156. These two extensions, 154 and 156, are sized to enter thenares of the nose in similar fashion to a nasal cannula oxygen supply.These extensions, 154 and 156, are flattened in one dimension, asdepicted in FIGS. 8A and 8B, and are shown angled at about 15 degrees ina second dimension, as viewed in FIG. 8B. This angle of inflection, 170,is properly drawn from a line drawn from one edge of the main section,152. 168 The first approach described above for the nasal oximeter probein FIGS. 2A-D is used to protect the components of the combined nasalpulse oximeter probe, 150, from moisture and contamination. A clearplastic covering, shown as 161 in FIG. 8A, is placed over, to cover,each distal half of the two extensions, 154 and 156. It is noted that inthe embodiment shown, the molded shell, 169, that forms and covers themain section, 152, also covers the approximately proximal half of thetwo extensions, 154 and 156. Either this, or a separate resilientinsert, provides a support for the upper, or distal halves of theseextensions, but does not cover the front and rear sides, nor the innersides, 165, of these extensions. To cover these exposed sides, a clearplastic covering, 161, is constructed, fitted over, and adhered to theexisting components to form an integral protective exterior surface withthe molded outer shell, 169. Such plastic covering, 161, typically ismanufactured by heat sealing pre-cut and/or pre-formed pieces to form afitted covering over the distal halves of extensions 154 and 156. Thenthis is shrink-wrapped over the components of the distal half of the twoextensions, 154 and 156. The plastic covers, 161, preferably do notinterfere with light transmission in the critical wavelength ranges ofthe LEDs 162 and 164. Apart from heat-shrink sealing, other means ofattaching the plastic covers, 161, to the extensions 154 and 156,include, but are not limited to, sonic welding, spot gluing, hot gluing,press fitting, and other such methods of attachment, as are employed inthe art, that are used to attach components of a medical device forentry into an orifice of a living subject. Also, other means ofproviding a protective covering, such as are known to those skilled inthe art, may be used instead of the above-described approach.

Further, using the shrink-wrapping construction described above to coverthe distal halves of the extensions 154 and 156, and dimensioning thespacing between the extensions 154 and 156 as indicated above for anon-contiguous fit, the extensions 154 and 156 are found to fit withoutirritation to the mucosal cells lining each side of the interior septum,as from a rough or uneven surface. For example, without being limiting,when using heat sealing plastic as the covering, 161, the thickness ofthis material, and any finish on the adjoining edge, will affect theextent of a sensible ridge at the junction of the covering, 161, and themolded outer shell, 169, but nonetheless provide a comfortable fit.

The nasal septum extends in the midline from the tip of the noseanteriorly to the posterior border of the hard palate posteriorly. It isbordered inferiorly by the roof of the mouth (the hard palate) andsuperiorly by the floor of the cranium. As to a specific area of thenasal septum that is preferred for use of a nasal pulse oximeter probesuch as the one depicted in FIGS. 8A-B, at least one highlyvascularized, and thus more suitable, area of the nasal septum islocated approximately 0.5-1.0 cm. from the posterior border of thenostril and approximately 2.0-2.5 cm. superior to the floor of the nasalcavity in the midline. Being more highly vascularized, such therebyprovides more consistent and reliable signals than less vascularizedareas that are, relative to this, more proximal (the tip of the nose) ormore distal (further posterior towards the back of the nasal cavity). Inparticular, and more specifically, the highly vascularized area of theseptum, known alternately as Kiesselbach's plexus and Little's area, isa preferred target area for detection of blood oxygen saturation levelsby a nasal pulse oximeter probe of the present invention.

The pulse oximeter nasal probe of the present invention is designed sothat, when properly positioned, it passes its light through such highlyvascularized areas. In the particular device shown in FIGS. 8A,B, anangle of inflection, 170, is shown between plastic housing, 152, and thetwo extensions, 154 and 156. This angle properly is measured as aninterior deviation from a straight line extended from the plastichousing, 152. In preferred embodiments, the angle of inflection, 170, isbetween about 0 and about 33 degrees, in more preferred embodiments, theangle of inflection, 170, is between about 10 and about 27 degrees, andin even more preferred embodiments, the angle of inflection, 170, isbetween about 10 and about 20 degrees. In FIG. 8B, the angle ofinflection, 170, is about 15 degrees. This angle has been found toprovide superior results in testing.

Further, it is noted that in typical use contact by an inner face of oneextension with nasal mucosal tissue interior to the columella precludescontact by the inner face of the other extension with the nasal mucosaltissue interior to the columella. Further, in many if not mostinstances, where there is a snug fit against the columella, there islittle or no contact by the more distal, inward sections of therespective extensions against the nasal mucosal tissue interior to thecolumella. Where a patient has a substantially deviated septum, theremay be contact by one extension on one side, but this is believed, inmost cases, to preclude contact by the other side once interior of anycontact with the columella.

Thus, for the embodiments depicted in FIGS. 2 and 8, a most common fitwith a nasal septum, when the respective device is in use, is thatcertain areas of the inner faces of the extensions only occasionally orlightly contact a portion of the tissue of the interior septum wall.Such portion is typically a protruding portion. It has been learned thatthis orientation, where the extensions bearing the light-generating andthe light-detecting structures, does not and need not press against bothsides of the nasal septum. Surprisingly, relative to prior artteachings, pressing against the tissue of the septum wall is not neededin order to obtain good pulse oximetry data.

As noted above, in certain embodiments contact with the nasal interiorseptum mucosal tissue is avoided or minimized by one or more of: sizingof the probe (particularly spacing between opposing inner faces),flexibility of the material used, other design features, and lack ofdesign and/or structure to compress or clip any part of the probe to thetissue of the nasal septum. Thus, in various more preferred embodiments,the inner sides (i.e., 65 or 165), of the two extensions, (i.e., 54 and56 or 154 and 156), if they ever contact the tissue (mucosal nasallining) of the interior septum, do so lightly, resting without excessivepressure, so as to avoid the development of necrosis of the mucosaltissue. This applies even when the nasal probe is used over extendedperiods of time. Also, it is noted that a snugly fitting probe, asdescribed in certain embodiments and within its broader context,comprises probes that contact comfortably the columella, whilstremaining spaced from (i.e., facing, adjacent to), the tissue of thenasal interior septum.

Further, referring to FIG. 8A, in general, the two extensions, 154 and156, are angled so that upon insertion and proper placement intoposition in the nostrils, the LEDs 162 and 164, located on extension156, emit light directed through a region that includes a preferred areaof the nasal septum. Most preferably, the LEDs 162 and 164, located onextension 156, direct light exclusively through the highly vascularizedregion of the septum known alternately as Kiesselbach's plexus andLittle's area (or, in The Principles and Practice of Rhinology, JosephL. Goldman, Ed., John Wiley & Sons, New York, 1987, Kiesselbach's plexusis “in” Little's area). Empirically, in certain evaluations, this highlyvascularized region, referred to herein as Kiesselbach's plexus, ismeasured to be located approximately 2.0 cm upward and approximately 1.0cm inward (toward the back of the head) from the tip of the anteriornasal spine. Kiesselbach's plexus is the region of the nasal septumwhere the terminal branches of at least two arteries meet and supply thetissue. These major terminal branches in Kiesselbach's plexus are thoseof the nasal septal branch of the superior labial branch of the facialartery and the anterior septal branch of the anterior ethmoidal artery(see, for example, plate 39 of Atlas of Human Anatomy, 2.sup.nd Ed.,Frank H. Netter, M.D., Novartis, 1997). Some terminal branches of theposterior septal branch of the sphenopalatine artery may also be foundin more posterior regions of Kiesselbach's plexus.

Also, because Kiesselbach's plexus actually is comprised of a region ofhighly vascularized tissue, rather than a discrete point, and givenanatomical variation among persons, a range of approximately +/−0.25 cmfrom the above indicated measured point also is acceptable as a targetarea to obtain unexpected superior results with a nasal pulse oximeterprobe. It also is recognized, based on the approximate size of theKiesselbach's plexus, that placing the probe so it measures saturationwithin a range as large as approximately +/−0.75 cm from the measuredpoint may also provide these unexpected superior results (by having thelight pass through this highly vascularized region). However, given thevariations noted above, this is less preferred than the range ofapproximately +/−0.25 cm. from the measured point. Under certaincircumstances, a range of approximately +/−0.50 cm. from the measuredpoint is considered acceptable. Given the basic morphology and sizing ofthe nares, design and placement of nasal pulse oximeter probes such thatthey pass light through nasal septum tissue within these larger ranges,but not within the smaller approximately +/−0.25 cm. range, frequentlyrequires probes of the present invention that are designed to havesmaller (i.e., thinner, narrower) profiles than the profile depicted inFIGS. 8A and 8B. This allows these probes to come closer to the outwardor inward structures of the nares and maintain patient comfort.

Also, for any of these ranges to target Kiesselbach's plexus, it isappreciated that the angle of a particular individual's lip in relationto the nose, and the placement of the nasal probe sensor on the upperlip, affect the exact location of the probe's light producing and lightsensing components on the plexus. As noted, it has been learned that anasal pulse oximeter, such as is depicted by 150 (with or without theoxygen cannula element), that has an angle of inflection, 170, of about15 degrees, has been found to provide superior results in testing. This15 degree angle to reach Kiesselbach's plexus with the light-generatingand the light-detecting components, in order to obtain superior sensingdata, takes into account that for many patients, there is an angle ofthe upper lip, tilting about 15 degrees. This is represented in FIG. 11,a facial profile. FIG. 11 also shows an angle, from a true vertical,starting from the opening of the nostril at the medial end, 171, ofabout 30 degrees that generally leads toward the desired area forobtaining pulse oximeter data, Kiesselbach's plexus. This 30 degreeangle includes the benefit of the approximately 15 degree angle of theupper lip, 173, upon which the nasal probe of the present invention isplaced. Thus, with this angle of the upper lip, in combination with a 15degree angle of the nasal probe, the light generating and lightdetecting components of the nasal probe are positioned at the desiredvascularized area, generally located along the 30 degree angle inwardand upward from the opening of the nostril at the medial end, 171. Oneexample of a nasal probe with a 15 degree angle, or bend, is shown inFIG. 8B. It is noted, however, that a nasal probe with such angle may bewith or without a cannula.

However, it is appreciated that the shape and angle of person's upperlip, and orientation to the nasal cavity, do vary. Thus, in certainembodiments, it is desirable to adjust the exact angle of the nasalprobe in relation to the upper lip (such as by gently twisting it as itis being secured to the upper lip) to obtain the most preferred area fordata. Also, optionally, the pulse oximeter is comprised of circuitry anddata output that provides a “perfusion index” to assist in improvedplacement of the probe so that the light-generating and light-detectingcomponents are placed in or near to the desired Kiesselbach's plexus. Asknown in the art, the perfusion index is the ratio between the pulsatileand the non-pulsatile components of the light that reaches thelight-detecting component. This provides a means to find which positionhas a greater pulsatile component, and can assist, when needed, inorienting a nasal probe to obtain a superior or the preferred site. Itis noted, however, that in trials, the probe having a bend of 15degrees, as shown in FIG. 8B, has been found to provide reliable datafor 30 patients tested to date without a need for subtle ortime-consuming adjustment of position on the upper lip.

Also shown in FIG. 8B is a conduit for oxygen (or oxygen-rich air orother gas mixture), 180, and a conduit, 182, within which areelectrically conductive wires (or other types of signal transmissionmeans, such as fiberoptic cable) to pass electrical signals to and fromthe two light-emitting diodes, 162 and 164, and the opposingphotodetector, 166. 180 Means of stabilizing the probe, 150, such aselastic straps (not shown) from any part of the device that span thehead of the patient, typically are employed, and depend on the type ofapplication and the comfort requirements of the user. More particularly,in order to stabilize the desired position of the nasal probe of thepresent invention (whether it is with or without a cannula), severalspecific approaches are useful. One approach to reversible attachment ofthe nasal probe to the patient is to apply tape to all or part of thepatient's upper lip, where the side of the tape to the patient's upperlip has an adhesive suited for the purpose and desired contact period,and the other, exposed side has one or more sections of either the hookor the loop of hook-and-loop type fabric. The side of the nasal probe torest on the upper lip (“back side”) is comprised of one or more sectionsof the hook-and-loop type fabric to complement the sections on thetape's exposed side, and by virtue of alignment and pressing together ofthe sections on the nasal probe and the upper lip, the nasal probe ispositioned on the upper lip. This type of reversible attachment can bemodified as needed, particularly when the strength of the adhesion ofthe hook-and-loop type fabric is lessened just to the strength needed tomaintain the probe in position in view of the typical range of forcesacting to dislodge it. A variation is to apply tape to the back side ofthe nasal probe, where the tape has adhesive on the side toward theprobe, and hook-and-loop type fabric on the opposite side, facing andattachable to the hook-and-loop type fabric on the tape of the upperlip.

Another approach to reversible attachment of the nasal probe to thepatient is to apply double-sided adhesive tape to all or part of thepatient's upper lip. Then the back side of the nasal probe is pressedagainst the adhesive on the upward-facing side of the double-sideadhesive tape. A variation is to apply the double-sided adhesive tapefirst to the back side of the nasal probe, then orient the probe intoits position against the upper lip with the extensions in the nares, andthen press against the upper lip to obtain adhesion thereto. When usingsuch approaches, it is advantageous to have a stabilizer (such as 58, inFIG. 1, there shown simply as a flat plate flush with and extendingdownward from the inside edge of the lower plane of the extensions 54).This provides additional surface area for contact with the tape, andimproves the stability of the reversible bonding with the upper lip, andthereby helps maintain a proper orientation to the desired vascularizedareas for detection of the condition of the arterial blood and its flow.

Yet another approach to reversible attachment of the nasal probe to thepatient is to apply single-sided adhesive tape over the top of the nasalprobe. This is done before or after the nasal probe has been positionedwith the extensions in the nares and the back side against the upperlip, and the tape is pressed into the skin of the face adjoining thenasal probe, to secure the probe in place.

As for the probes depicted in FIGS. 1 and 2A-D and described above,timed electrical impulses from a pulse oximeter monitor system passthrough two wires or other signal transmission means (not shown) incables held within conduit passing within 182 to produce the light fromLEDs 162 and 164. At least one photodetector, 166, is positioned withinextension 154 to face and oppose LEDs 162 and 164 on extension 156. Thephotodetector 166, which typically is a light-sensing photodiode,detects changes in the light emitted by the LEDs 162 and 164 as thatlight is differentially absorbed between and during pulses across thecapillaries of the septum tissue between the two extensions, 156 and154. In one embodiment, LED 162 emits light around 650-670 nm, and LED164 emits light around 880-940 nm. The electrical impulses are timed tobe offset from one another, so that the light from each of the two LEDs,162 and 164, is emitted at different times. The photodetector, 166,detects the light passing through the septum of the nose, which issituated between extensions 156 and 154 when the probe 150 is in use. Asdiscussed above, loss of signal through vascularized tissue such as thenasal septum is due both to background tissue absorption and theabsorption by the blood in the arteries, which expands during a pulse.The signals from photodetector 166 pass through conductors (not shown)to the processor of the monitor system (not shown). As examples, notmeant to be limiting, a single cable passing from one side of thedevice, 150, or two cables that may form a loop that may lie above theears of the patient, or join to form a single cable (not shown), passsignals to the two LEDs, 162 and 164, and from the photodetector 166. Inone preferred embodiment, a single cable, formed from the joining of twocables leading from the device, 150, terminates in an electrical plugsuited for insertion into a matching socket in the pulse oximetermonitor system (not shown). In another preferred embodiment, the singlecable terminates by connecting to an adapter cable, which in turnconnects to a socket in the pulse oximeter monitor system (not shown).In a typical application, the signals from the light-sensingphotodetector, 166, are ultimately received and processed by a generalpurpose computer or special purpose computer of the monitor system (notshown).

Per the disclosure preceding this example, this combination nasal pulseoximeter is used either in combination with the needed computerprocessing to interpret and provide a viewable (or audible in the caseof an alarm) data output of arterial blood oxygen saturation for theuser or health care worker, or, in alternative embodiments, thisfunction is further combined with the means to regulate and adjust theflow of oxygen or oxygen-rich gas that is being delivered by adjustmentof a valve controlling such flow.

Example 6

The present invention also is adapted for embodiments which utilize, incombination, pulse oximeter detection of arterial blood oxygensaturation, in combination with a supply of oxygen, air, or a gasmixture providing a variably supply of oxygen, where the flow rateand/or amount of oxygen provided in the gas mixture is controlled basedat least in part by the changes and levels of arterial blood oxygensaturation, as detected by the pulse oximeter. Applications for suchcombination devices (pulse oximeter/oxygen supply directed by controllerwith pulse oximeter data as an input) include, but are not limited to:self-contained breathing apparatuses (SCBA); self-contained underwaterbreathing apparatuses (SCUBA); high altitude breathing systems, andmedical gas delivery systems. The following figures and relateddisclosure provides only one, non-limiting embodiment to present thebasic concepts of the present invention as applied to a SCUBA regulator.FIG. 10 is used to depict a general control approach for this and othersystems described in this application.

FIG. 9A presents a diagram of a basic SCUBA regulator, 200, with keyfeatures described. The housing, 220, contains a diaphragm that sensesambient water pressure which is linked physically to adjust the deliverypressure to the user via regulation of the second stage regulator, alsowithin the housing, 220. A supply hose, 212, carries compressed air, orother gas mixtures, typically from a supply tank (not shown), to thesecond stage regulator (not shown) within the housing, 220. Upon demandfrom the user, whose mouth is fitted around the rubber mouthpiece, 201,the air or other gas from the hose, 212, passes through the second stageregulator, and through the mouthpiece, 201, to provide the user with asupply of air or other gas based on the flow pattern of the second stageregulator. Having the rate of this flow upon demand being variable,based in part on the type of regulator and its operating conditions andmaintenance, can result in waste of precious air supply. Also, when thepercent of oxygen or other gas in the air supply can be altered based ondata from a pulse oximeter, the body's physiological requirements can bebetter met, resulting in a safer and healthier dive experience.

FIG. 9B presents a diagram of the basic SCUBA regulator FIG. 9A, howeveralso comprising additional features of the present invention. Inparticular, a flexible arm 202 bearing two light-emitting sources, 204and 206, (typically LED's) is disposed in a place exterior to theposition of the lip of the diver using the regulator. The approximatethickness of the lip is represented in FIG. 9B by the distance, a.Flexibility of the arm 202, is by the nature of the material such asrubber and/or by spring loading. By such design, the arm 202 moveseasily away during fitting of the mouthpiece (i.e., the placement of thelip around the flange, 207, of the mouthpiece, and the teeth over thenubs, 209 (one is shown as a dashed rectangle to indicate position onthe inside surface of the flange). Then the arm, 202, presses againstthe lip or against the skin just below the lower lip, in such anorientation so that light emitted by the two light-emitting sources, 204and 206, is directed toward a photosensor, 208, inset into the outersurface of the rubber mouthpiece 201. This receives signals through thelower lip/flesh below the lip, which is sufficiently well-vascularizedto provide a representative reading of the body's oxygen statusexpressed as of arterial blood oxygen saturation. Wiring 210 passes datasignals between this pulse oximeter probe and the oximeter controller(not shown, end of wiring in figure coincides with end of supply hose,212). This interprets the data signals from the pulse oximeter probeand, based on the information received, directs a separate valve (notshown) to adjust upward or downward the level and/or pressure of oxygensupplied through the supply hose 212 to increase or decrease theabsolute or relative oxygen flowing to the regulator at the mouthpieceshown in FIG. 9B.

For SCUBA systems using HE/Ox mixtures, additional oxygen can beprovided when indicated by the data from the oximeter, and/or by amanual control (such as the diver pressing a button to increase, with asecond button to decrease oxygen flow incrementally). The sameapproaches apply to more complex dive gas mixtures, such as Triox(oxygen enriched air with helium) and Trimix (hypoxic oxygen, helium andnitrogen). By appropriate control mechanisms and algorithms (adjusted tocompensate for physiological differences at different depths), a diverusing such embodiments of the present invention extends the dive time ona particular quantity of oxygen, and/or has more oxygen when more oxygenis needed, and less oxygen when less oxygen is sufficient. This resultsin a safer, healthier dive experience.

The above disclosed improvements in the monitoring of blood oxygensaturation and adjustment of gases supplied to a SCUBA diver also applyto users of self-contained breathing apparatuses (SCBA) that are notused for underwater diving. For example, firemen and other emergencyworkers use SCBA in environments in which they may exert considerableenergy and have transient very high oxygen demands. The above-disclosedembodiments, and variations of these known to those of skill in therelevant arts, provide benefits to such users.

FIG. 10 provides a flow diagram of the general information and controlgeneration of the “pulse flow oxygen sensor” that controls the level orpressure of oxygen provided to a user wearing a nasal or mouth pulseoximeter sensor of the present invention in combination with the gassupply controlled by a controller receiving data input from that pulseoximeter sensor. Fundamentally, data signals from the pulse oximetersensor go to an arterial blood oxygen saturation/oxygen supply ControlCircuit. Based on analysis of these data signals using an appropriatealgorithm, the arterial blood oxygen saturation/oxygen supply ControlCircuit sends signals to a servodevice that adjusts an Oxygen ControlValve which receives oxygen under pressure from an oxygen source. Fromthe O.sub.2 Control Valve, oxygen is directed to a patient in need ofoxygen, where that patient is wearing the combined nasal or mouth pulseoximeter sensor of the present invention in combination with the gassupply cannula or mouthpiece.

Example 7

As described above, Kiesselbach's Plexus is a vascularized area in theanteroinferior part of the interior nasal septum, and is supplied bysphenopalatine, greater palatine, superior labia and anterior ethmoidarteries. These vessels originate from both the internal and externalcarotids and are the most frequent cause of epistaxis (nose bleed).

To demonstrate the utility of Kiesselbach's Plexus as a site for pulseoximetry, data was recorded from a more vascularized region of the nasalseptum (i.e., Kiesselbach's plexus) using a probe of the presentinvention in its intended positioning. This data was compared to datafrom two adjacent sampling sites, one inferior and posterior, and oneanterior and superior to Kiesselbach's plexus. Since all three samplingsites are capable of giving a signal for pulse oximetry with a standardpulse oximeter monitor, relative LED power provided a marker of utility.A lower LED power required to obtain a measurement indicates a strongersource signal. Such lower power requirement is apparent when the probeis placed so as to transmit light through the vascularized areaidentified as Kiesselbach's plexus. Also, as further discussed herein, astronger signal source in the nasal or cheek/lip areas generally provideimproved signals for use in plethysmography.

A nasal probe of the present invention, having a 15 degree inward angle,or inflection along its extensions, was utilized for the comparison.This probe has a side view similar to the probe in FIG. 8B. To obtainwhat is identified in FIG. 18A as “Approx. 0 Degrees,” the probe wasangled outward from its normal, desired position to approximate aposition for the light-generating and the light detecting componentsover the nasal septum that simulates a probe having straight extensions(i.e., not having the 15 degree inward inflection). FIG. 18B, identifiedas “Approx. 15 Degrees,” is the probe in its normal, desired position(see FIG. 11 and related discussion), with the 15 degree inflectionpositioning the light-generating and the light detecting components overthe nasal septum at a desired position that, in subjects tested to date,provides superior results. To obtain what is identified in FIG. 18C as“Approx. 30 Degrees,” the probe was angled inward from its normal,desired position to approximate a position for the light-generating andthe light detecting components over the nasal septum that simulates aprobe having such components further inward (anterior and superior) thanthe position obtained with the 15 degree-inflected probe seated on theupper lip. That is, based on the upper lip angle of 15 degrees, theprobe position for the data shown in FIG. 18C is approximately 45degrees inward of vertical (see FIG. 11 and related discussion).

The data indicates that the probe in its intended position, with theback of the probe's main section against the upper lip, providessuperior data. This is indicated by virtue of FIG. 18B's LED Powerreading of 66, compared to the LED Power readings of 108 and 102 forFIGS. 18A and 18C, respectively. Without being bound to a particulartheory, when the probe is in its intended position, it passes lightthrough the more vascularized section of the nasal septum (i.e.,Kiesselbach's plexus), and the standard algorithm of the pulse monitorobtains the desired data signals with a lower power to the LEDs. Thedata provided in this example is consistent with earlier testing whichdemonstrated, unexpectedly and advantageously, that superior pulseoximetry and plethysmography data is obtained when the distal end of thepulse oximeter probe extensions are designed so as to locate thelight-generating and the light detecting components to a desired morevascularized locus, i.e., Kiesselbach's plexus. Thus, it is furtherappreciated that various designs that have the end result of locatingthe light-generating and the light detecting components to the desiredmore vascularized loci as obtained by the probes of the presentinvention, such designs are within the scope of the present invention.For example, and without being limiting, FIG. 18D provides analternative design of an acutely angled nasal probe, 300, that achievesthe same positioning as a probe having a profile of the probe in FIG.8B.

Further, it is noted that in some subjects, a nasal probe of the presentinvention, when placed in the position as indicated above for FIG. 18B,provides data that, effectively, goes “off the scale.” Without beingbound to a particular theory, this is believed to be due topeculiarities of the algorithms used in the processor of a standardpulse oximeter, and/or the fundamental system logic of a finger pulseoximetry system. For example, the algorithm and processor of a standardfinger pulse oximeter system are designed to adjust light intensity fora probe positioned on a finger, where there is a relatively higherpercentage of less vascularized tissue compared to the nose, lip andcheek. In such circumstances, if a greater than expected amount of lightis received at the photodetector, this may indicate the probe hasslipped from the finger, or from the proper position on the finger. Forsuch algorithm, a strong signal may be considered erroneous.

To address problems of “off scale” readouts for nasal probe datacollected from some subjects, it has been further learned that varioustypes of “filters” can be implemented to eliminate this problem. Twogeneral approaches to “filtering” are electrical and light approaches.An example of the electrical approach is to place a resistor in seriesto both of the light producing LEDs. This proportionally decreases theamount of light emitted at both wavelengths. As to the light approach, afilter, such as a white material, a translucent or an opaque cover, canbe physically placed over all or part of the light-producing LEDs, overthe photodetector, or both, to reduce the light input into thephotodetector, such that a readable signal can be generated in suchsubjects. This reduces the amount of both wavelengths of light receivedat the photodetector without dramatically altering the ratios of suchwavelengths. Without being limited, yet another way to compensate forthe more vascularized, higher light output areas of the nose, lip andcheek is simply to use smaller light-detecting photodiodes. If theresponse curve for the smaller photodiode remains the same compared toits larger counterpart, just it active area reduced, this would keep thelight level ratios of the respective wavelengths proportional. Forinstance, a 0.4 mm size active area may be used instead of a 0.8 mm sizeactive area. Other methods as known to those of ordinary skill in theart can likewise be employed to deal with the higher signal,particularly for probes that are used in pulse monitor equipment withalgorithms designed for signals from finger probes. By adjusting theamount of light by any of the above means, and upon consequentadjustment of the output parameters of the oximeter, as many occur incertain units, the sensor output achieves a more acceptable range formonitoring.

In conclusion, the area of Kiesselbach's plexus across the nasal septumis the area in the nose of strongest signal for pulse oximetry asdemonstrated by this simple experiment. It is noted that even using afiltered probe and placing it anteriorly of Kiesselbach's plexus a powerlevel 2.5 times lower than what is required by the finger provides agood signal. As discussed above, one approach to locating this desiredsite is to use the probes having the desired bend, or angle ofinflection. Another approach, which may only be needed in a small numberof instances, is to use the perfusion index feature on a pulse oximeterdevice, and position where the index is highest.

Example 8

Several specific profiles of data are provided from patients whounderwent various procedures in a teaching hospital and who wore thepulse oximeter probes of the present invention. This data isillustrative of the value of the nasal probes of the present invention.For all figures below, the data designated as “PULSE OX 1” or “P-OX 1”is from a nasal probe measuring data across the interior nasal septum,the data designated as “PULSE OX 2” or “P-OX 2” is from a cheek/lipprobe measuring data across the cheek (below the lip), and the datadesignated as “PULSE OX 3” or “P-OX 3” is from a conventional fingerprobe.

FIG. 16A-C provides photoplethysmographic and arterial blood oxygenationdata from a patient who was undergoing coronary artery bypass surgery.Pulse oximeter probes of the present invention were placed in the noseand in the mouth (a cheek/lip probe), and a conventional probe wasplaced on a finger. FIG. 16A shows typical plethysmographic data fromall three probes prior to the switching to bypass. This figure alsoindicates that the blood oxygenation as measured by all three probeswere similar, as were the plethysmograph curves.

FIG. 16B shows data from about one minute after cardiac activity wasreinitiated and the blood flow and pressure returned following bypass,but during a low flow condition (which was done to repair a tear in theaorta). This demonstrates that both the nasal and the cheek/lip probeshad sufficient blood flow to obtain a plethysmograph and pulse andsaturation data, whereas the finger probe did not.

FIG. 16C shows data near the end of the surgical procedure, when bloodflow had returned to normal. All three sites are provided readable data.Also, although the plethysmographic data from the finger site appearsstronger (i.e., the peak is higher), it should be kept in mind that thisis the result of algorithms in the pulse oximeter that automaticallyadjust power and gain.

FIGS. 17A-C provide data from three different patients, all of whichexperienced cardiac arrhythmias at some time during the observationperiod. In all three examples, the nasal probe and the cheek/lip probeprovided clearer imaging of the arrhythmias than the finger probe. Also,as observable in FIG. 17D, taken from a fourth patient, the nasal probemost distinctly detected what appears to be a dicrotic notch (comparedwith the cheek/lip and finger probes). Also, it obtained this data withrelatively low energy being supplied to the LED.

Also, during testing with certain patients, given increased sensitivityfrom the nasal probe, it was observed that respiratory rate can beaccurately measured from the nasal photoplethysographs since the nasalprobe is more sensitive to volume changes. That is, changes in the“envelope” of the plethysmograph DC component indicates the breathingcycle, and this, upon quantification of these cycles, can estimaterespiratory rate. One example of this is provided in FIG. 18 a, wherethe space between the two vertical lines represents one respirationcycle.

Use of the nasal or cheek probes independently or in conjunction withthe finger probe can also be used to evaluate the effects on cardiacoutput, blood pressure and perfusion in spontaneously breathing andmechanically ventilated patients. For instance, when a normal subjectbreathes spontaneously, there is little or no observable effect on theplethysmograph from a finger probe. However, both the nasal and cheekprobes demonstrate a drop in the “envelope” of the plethysmograph. Thisis explained by an increase in venous return to the right side of theheart and a decrease in blood flow from the left ventricle due tonegative pressure relative to atmospheric pressure produced in thethoracic cavity during normal breathing. This fall in the “envelope” ofthe plethysmograph is exaggerated during spontaneous breathing againstresistance, such as pulmonary diseases that narrow the airways andduring hypovolemia or low cardiac output. In addition to the fall in the“envelope” of the plethysmograph, there is often a decrease in themaximum amplitude of the plethysmograph, which becomes more pronounced(a greater decrease) with hypovolemia, poor cardiac output or poorperfusion. Comparing the nasal or cheek plethysmographs with the fingerplethysmograph may be an additional means to follow these effects overtime.

During mechanical ventilation, changes opposite to those observed withspontaneous breathing occur in both the “envelope” of the plethysmographand the amplitude. Positive pressure ventilation increases intrathoracicpressure, which in turn increases blood flow from the left ventricle andresults in a rise above baseline in the “envelope” and an increase inthe amplitude of the plethysmograph. Hypovolemia and/or poor cardiacoutput diminish these salutary effects. FIGS. 18A-C demonstrate theeffects of positive pressure ventilation on increasing vasodilatation orhypovolemia, such as seen during anesthesia. In FIG. 18A each positivepressure ventilation results in a rise in the plethysmograph “envelope”.In FIGS. 18B and C there are great excursions in the plethysmograph asthe patient becomes vasodilated and the amplitude of the plethysmographdecreases.

Further, evaluation of the plethysmograph during both spontaneous andmechanical ventilation can be used to determine the optimal level ofpositive end expiratory pressure (PEEP) for a patient. PEEP is animportant parameter for optimizing the oxygenation of a patient.Depending on the volume and cardiac status of a patient, differentlevels of PEEP can be tolerated. Since a higher PEEP raises the baselineintrathoracic pressure, it impedes venous return to the heart and cancause decreased cardiac output. If a subject is hypovolemic, vasodilatedor has poor cardiac output, excessive PEEP may lead to hypotension,lactic acidosis and eventually shock. If inadequate PEEP is given, thepatient will be hypoxemic, which can also lead to lactic acidosis andshock. Thus, there is an optimal PEEP for each subject depending on hisor her pulmonary, volume and cardiac status. Excessive PEEP narrows theamplitude of the plethysmograph and causes exaggerated excursions in the“envelope” of the plethysmograph.

Evaluation of the “envelope” of the plethysmograph and the effects ofventilation on the amplitude of the plethysmograph can be used toprovide a level of PEEP that allows adequate oxygenation withoutcompromising cardiac output. If oxygenation remains poor at a givenlevel of PEEP, volume expansion with fluids and/or drug treatment canimprove cardiac output and allow the patient to tolerate the higherlevel of PEEP. Evaluation of the plethysmograph provides a non-invasivemeans of determining the effects of positive pressure ventilation andPEEP on the cardiac output of the patient.

It is noted that an appreciation of data obtainable from pulse oximetryprobes is found in the scientific article, “The peripheral pulse wave:information overlooked,” W. B. Murray and P. A. Foster, J. Clin.Monitoring 12:365-377, 1996. This reference discusses in detail thebases for changes in the wave form obtainable from pulse oximeterperipheral probes, and the significance of changes in such wave formsduring anesthesia. All material in this reference is hereby particularlyincorporated by reference into this disclosure. Further, it is notedthat this reference focused on the use of the ear, or peripherallocations, and so did not fully appreciate the types and improvedquality of data obtainable from a desired vascular site of the interiornasal septum, or from the cheek/lip probe, as described herein. Also, itis appreciated that the probes of the present invention find utility notonly in patients who are inactive, such as those undergoing anesthesiaduring surgery, but also in patients who are awake and, selectively,ambulatory.

Thus, as observable from the above figures, the use of a nasal probe ofthe present invention, which does not require pressure against theseptum wall to operate, advantageously provides photophethysmographicdata that is able to detect cardiac, pulmonary, and other abnormalitiesnon-invasively, and better than more remote sites, such as a finger or atoe. While not being bound to a particular theory, this is believed dueto the combination of: 1) not applying pressure to the vascularized site(thereby not damping more subtle signals of heartbeat patterns, etc.);2) accessing an arterial bed supplied by a major vessel, the internalcarotid artery; and 3) accessing this arterial bed in a position that isnot subject to additional noise and dampening (as is found in extremitysites, such as the finger or toe).

Example 9

In many instances when pulse oximetry is being used to detect, forinstance, arterial blood oxygen saturation, and/or, when plethysmographyis being used to detect other cardiovascular parameters, there also is adesire or need to measure carbon dioxide during exhalation, particularlythe end tidal carbon dioxide of the patient. It is recognized, forinstance, that monitoring the carbon dioxide during the exhalation cyclemore quickly detects airway obstruction than pulse oximetry, and, wherethere is an endotracheal intubation, provides the most reliableindicator of proper intubation. A graph of the concentration of carbondioxide in exhaled gas plotted over time is referred to as a capnogram.An instrument capable of displaying only end tidal values is called acapnometer, while an instrument capable of graphically displaying endtidal carbon dioxide is called a capnograph. The shape of the capnogramreveals information about the integrity of a breathing system and thephysiology of the patient's cardiorespiratory system. As such,capnography is the preferred method of end tidal carbon dioxidemonitoring.

Accordingly, another aspect of the present invention is the combinationof the nasal pulse oximeter of the present invention with samplingstructures that direct exhaled gas for carbon dioxide measurements toprovide data for either a capnometer or a capnograph.

For instance, and not to be limiting, FIG. 19A depicts a combinationpulse oximeter/cannula/carbon dioxide sampler, 400. Here the body ofnasal probe, 450, is substantially comprised of extensions, 454 and 456,each sized to enter the nares, and integrally molded main section, 452,and is joined with a cannula/carbon dioxide sampler, 410, that isdesigned in accordance with U.S. Pat. No. 6,422,240 B1, issued Jul. 23,2002. One of the extensions, 454 comprises the light-generatingcomponents (not specifically shown, but within 470 and includingstructures such as LEDs 62 and 64 in FIG. 2A-D). The other extension,456, comprises a light detecting component(s) (not specifically shown,but within 472 and including structures such as photodetector 66 in FIG.2A-D). Connecting wiring, 480, passes between the light-generating andlight-detecting components and the pulse oximeter itself, and passesthrough a wire conduit, 482, that selectively travels contiguously for alength with either the oxygen supply tube, 484, or the carbon dioxidesampling tube, 486 (shown in FIG. 19A traveling with the oxygen supplytube, 484). Attaching means, 490, join the nasal probe, 450, with thestructure of the cannula/carbon dioxide sampler, 410, and may be of anytype known in the art, including, but not limited to: adhesive (i.e.,plastic glue, thermoplastic glue), double-sided tape, and the like.

In operation, oxygen from a supply source (not shown), delivered viaoxygen supply tube 484, is released at the apertures, 430, in front ofthe patient's nose and above the patient's mouth (seen better in FIG.19B), and upon inhalation, some of this oxygen is taken up and passes tothe lungs of the patient. Upon exhalation, whether from nose and/ormouth, exhaled gases are collected in one or more of the three intakeports, 440 (two nasal, one oral). The exhaled gases are collected andpassed through the tube, 486, to a carbon dioxide detector (not shown).At the same time that this repeatedly occurs, advantageously, pulseoximeter data is collected by the nasal probe, 450, by the meansdescribed elsewhere in this disclosure. This data, communicated byconnecting wiring, 480, is analyzed by a pulse oximeter and the outputdisplayed on an appropriate output monitor (not shown).

FIG. 19B depicts the combination nasal probe/cannula/carbon dioxidesampler, 400 positioned on the face of a patient. Arrows 490 depict theflow of oxygen from a dual-gas manifold, 488, which directs oxygenreceived from the oxygen supply tube, 484. During exhalation, theexhaled breath gases, which include carbon dioxide, are collected fromthe intake ports, 440, one in the mouth (to collect when a patient is“mouth breathing”), and one from each nostril. The nasal pulse oximeterprobe, 450, is secured along the top edge of the manifold, 488, andalong the adjacent sides of the tube wall of the two nasal intake ports,440. Details of the nasal pulse oximeter probe, 450, are observable inFIG. 19A.

Example 10

As for the combinations described above for the nasal probe, thelip/cheek probe of the present invention also is combined with 1) acarbon dioxide sampling device, 2) a source of oxygen or oxygen-richgas; or 3) both of these.

For example, and not to be limiting, FIG. 20 depicts one embodiment of acombination of the lip/cheek probe of FIG. 1, 10, in combination with acarbon dioxide sampler, 90, for use in capnography. A flexible hollowtube, 92, communicates between a three-pronged sampling end, 94, and theactual carbon dioxide detector (not shown). Two upper prongs, 95 and 96,are sized and spaced for insertion into the nares of the nose of thepatient (not shown), and one lower prong, 97, is sized for insertioninto the mouth of the patient (not shown), or for terminating outside ofthe mouth of a patient (not shown), to take up sample outside the mouth.A section of the tubing, 98, is adjustably engaged to a correspondingsection of the boot, 8. For instance, the distance between the boot, 8,and the three-pronged sampling end, 94, is adjusted so as to be withoutkinking or torsion, thereby providing for a comfortable fit. Thereversible and adjustable engagement of the tubing between this sectionand the three-pronged sampling end, 94, is effectuated by any means forattaching known in the art, which includes, but is not limited to:hook-and-loop adjoining fabric sections, one or more loops of flexibleplastic or other material encircling both the boot, 8, and the sectionof the tubing, 98, a snap fitting with the snap on the tube, 92,slidably movable along said tube, 92. It is noted that in otherembodiments, not shown, the tubing, 92, engages a part of the probe, 10,other than the boot, 8 (such as when the probe, 10, is not comprised ofa boot). Such means for attaching the tubing, 92, is present on allsides of the boot (or other part of the probe, 10), or alternativelyonly on one or more of the sides most likely to be used (i.e., the sidesituated in an upper position when the probe, 10, is placed so thebridging section, 2, of the probe, 10, is positioned in or near onecorner of the mouth, with the cable leading over one ear).

Additionally, the three-pronged sampling end, 94, is taped or otherwisesecured to the upper lip, as may be appropriate for a particularpatient. In use, the carbon dioxide concentration is measured over timeand volume, and one or more capnographs is obtainable. Such combinedapparatus has use with persons undergoing sleep studies and otherresearch, and in other applications where oxygen need not be supplied.

The lip/cheek probe also may be combined with a cannula device toprovide gas, such as oxygen or an oxygen-rich gas mixture, to a patientin need thereof. For instance, and not to be limiting, the tubingassembly designated as 90 in FIG. 20 alternatively is used to supplyoxygen or an oxygen-rich gas mixture to both the nose and mouth area (toaccommodate mouth breathing) rather than to sample exhaled breath asdescribed above. More generally, any number of designs of cannuladevices as are known in the art are so combined, to supply such gas tothe nose, to the mouth, or to both.

Thus, the lip/cheek probe of the present invention may be combined toform a single, operational unit with any other style of oxygensupply/carbon dioxide sampler device, that is, an integralmulti-functional device. This provides the advantage of obtainingreliable data, such as for arterial oxygen saturation, while onlyoccupying essentially the same space and path of tubing/wiring, as doesthe oxygen supply/carbon dioxide sampler device alone. The data from theprobe can be integrated with the data from the capnography unit toobtain a better picture of the patient's respiratory and circulatoryfunction and condition. Additionally, as for other types of probesdescribed above, an additional feature is added, namely a control meansto adjust the flow rate of the gas that is provided, where such controlis directed by the blood oxygen saturation data obtained from the probe.

Although depicted above as separate units combined after production, thecombinations described above alternatively are integral units designedand sized such that the lip/cheek probe therein functions as describedin this disclosure. Also, protective sleeves, as described for thelip/cheek probe alone, are envisioned to be shaped and manufactured inaccordance with the teachings herein, and used for these multi-functiondevices.

Preferably, the probes and sleeves are easily fabricated from low costmaterials and are adaptable for use in an operating room, intensive careunit, emergency department, post-surgery recovery areas and other areasto treat patients in need of hemodynamic monitoring. The monitoringsystem is particularly applicable for use with patients in whomhypotension or poor perfusion are problematic. In addition, themonitoring system is particularly well suited for use with multi-traumaand thermally injured patients who either have severe peripheralvasoconstriction or have severely damaged or destroyed peripheralvascular beds. Through combining at least two pulse oximeters capable ofmeasuring desired parameters at at least two locations into a singlemonitor system, the present invention provides a more accurateassessment of perfusion and resistance in patients, than any of thepresently available single probe pulse oximeters.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and the scope of the appended claims.

1. A method of monitoring respiration in an individual, comprisingisolating a DC component of a plethysmograph; and monitoring with acomputer changes in an envelope of the isolated DC component of theplethysmograph to monitor respiration.
 2. The method of claim 1, furthercomprising quantifying the changes in the envelope of the isolated DCcomponent to determine respiratory rate.
 3. The method of claim 1,wherein the plethysmograph is obtained from a plethysmography probesecured at a central source site.
 4. The method of claim 3, wherein thecentral source site is the nasal alar.
 5. The method of claim 1, whereinthe plethysmograph is obtained from a spontaneously breathingindividual.
 6. The method of claim 1, wherein changes in the envelope ofthe isolated DC component are used to determine the optimal level ofpositive end expiratory pressure (PEEP).
 7. The method of claim 6,wherein in the method further comprises adjusting the level of PEEP inresponse to the changes in the envelope of the plethysmograph.
 8. Themethod of claim 1, further comprising monitoring respiration with aseparate monitoring sensor.
 9. The method of claim 8, wherein theseparate monitoring sensor detects nasal air pressure, nasal air flow,or both.
 10. The method of claim 8, wherein the separate monitoringsensor comprises a capnography sensor.
 11. A system for monitoringrespiration in an individual comprising: a computer configured toisolate a DC component from a plethysmograph, and to evaluate changes inan envelope of the isolated DC component to determine a breathing cycleof the individual.
 12. The system of claim 11, wherein the computer isfurther configured to determine respiration rate from the changes in theenvelope of the isolated DC component.
 13. The system of claim 11,further comprising a pulse oximetry probe configured to secure to thenose of the individual.
 14. The system of claim 13, wherein the pulseoximetry probe is configured to secure to the nasal alar of theindividual.
 15. The system of claim 11, wherein the system is furtherconfigured to increase or decrease a supply of oxygen to the individualin response to the changes in the envelope of the isolated DC component.